Instruct: Given a question, retrieve relevant documents that can help answer the question.
Query: When did construction begin on the Parthenon?
In the mid-5th century BC, when the Athenian Acropolis became the seat of the Delian League and Athens was the greatest cultural centre of its time, Pericles initiated an ambitious building project that lasted the entire second half of the century. The most important buildings visible on the Acropolis today — the Parthenon, the Propylaia, the Erechtheion and the temple of Athena Nike — were erected during this period. The Parthenon was built under the general supervision of the artist Phidias, who also had charge of the sculptural decoration. The architects Ictinos and Callicrates began their work in 447 BC, and the building was substantially completed by 432, but work on the decorations continued until at least 431.
The Pantheon (, ; , from Greek "Pantheion", "[temple] of all the gods") is a former Roman temple, now a church, in Rome, Italy, on the site of an earlier temple commissioned by Marcus Agrippa during the reign of Augustus (27 BC – 14 AD). It was completed by the emperor Hadrian and probably dedicated about 126 AD. Its date of construction is uncertain, because Hadrian chose not to inscribe the new temple but rather to retain the inscription of Agrippa's older temple, which had burned down.
The Parthenon Marbles (Greek: Γλυπτά του Παρθενώνα), also known as the Elgin Marbles (), are a collection of Classical Greek marble sculptures made under the supervision of the architect and sculptor Phidias and his assistants. They were originally part of the temple of the Parthenon and other buildings on the Acropolis of Athens.
In 1975, the Greek government began a concerted effort to restore the Parthenon and other Acropolis structures. After some delay, a Committee for the Conservation of the Acropolis Monuments was established in 1983. The project later attracted funding and technical assistance from the European Union. An archaeological committee thoroughly documented every artifact remaining on the site, and architects assisted with computer models to determine their original locations. Particularly important and fragile sculptures were transferred to the Acropolis Museum. A crane was installed for moving marble blocks; the crane was designed to fold away beneath the roofline when not in use. In some cases, prior re-constructions were found to be incorrect. These were dismantled, and a careful process of restoration began. Originally, various blocks were held together by elongated iron H pins that were completely coated in lead, which protected the iron from corrosion. Stabilizing pins added in the 19th century were not so coated, and corroded. Since the corrosion product (rust) is expansive, the expansion caused further damage by cracking the marble.
Today the Parthenon, which functions as an art museum, stands as the centerpiece of Centennial Park, a large public park just west of downtown Nashville. Alan LeQuire's 1990 re-creation of the Athena Parthenos statue is the focus of the Parthenon just as it was in ancient Greece. The statue of Athena Parthenos within is a reconstruction, to careful scholarly standards, of the long-lost original: she is cuirassed and helmeted, carries a shield on her left arm and a small statue of Nike (Victory) in her right palm, and stands high, gilt with more than of gold leaf; an equally colossal serpent rears its head between her and her shield. Since the building is complete and its decorations were polychromed (painted in colors) as close to the presumed original as possible, this replica of the original Parthenon in Athens serves as a monument to what is considered the pinnacle of classical architecture. The plaster replicas of the Parthenon Marbles found in the naos (the east room of the main hall) are direct casts of the original sculptures which adorned the pediments of the Athenian Parthenon, dating back to 438 BC. The surviving originals are housed in the British Museum in London and at the Acropolis Museum in Athens.
In March 2011, archaeologists announced that they had discovered five metopes of the Parthenon in the south wall of the Acropolis, which had been extended when the Acropolis was used as a fortress. According to "Eleftherotypia" daily, the archaeologists claimed the metopes had been placed there in the 18th century when the Acropolis wall was being repaired. The experts discovered the metopes while processing 2,250 photos with modern photographic methods, as the white Pentelic marble they are made of differed from the other stone of the wall. It was previously presumed that the missing metopes were destroyed during the Morosini explosion of the Parthenon in 1687.
The decades that followed became known as the Golden Age of Athenian democracy, during which time Athens became the leading city of Ancient Greece, with its cultural achievements laying the foundations for Western civilization. The playwrights Aeschylus, Sophocles and Euripides flourished in Athens during this time, as did the historians Herodotus and Thucydides, the physician Hippocrates, and the philosopher Socrates. Guided by Pericles, who promoted the arts and fostered democracy, Athens embarked on an ambitious building program that saw the construction of the Acropolis of Athens (including the Parthenon), as well as empire-building via the Delian League. Originally intended as an association of Greek city-states to continue the fight against the Persians, the league soon turned into a vehicle for Athens's own imperial ambitions. The resulting tensions brought about the Peloponnesian War (431–404 BC), in which Athens was defeated by its rival Sparta.
In order to avoid the difficulty of giving an exhaustive list of deities when devoting a temple or sacred building, a structure explicitly dedicated to "all deities" also came to be referred to as a "Pantheon". The best known of such structures is the Pantheon of Rome, first built between the years 27 BCE and 14 CE. The building standing today was constructed on the same site around 126 CE. It was dedicated to "all gods" as a gesture embracing the religious syncretism in the increasingly multicultural Roman Empire, with subjects worshipping gods from many cultures and traditions. The building was later renovated for use as a Christian church in 609 under Pope Boniface IV.
The Augustan Pantheon was destroyed along with other buildings in a huge fire in the year 80 AD. Domitian rebuilt the Pantheon, which was burnt again in 110 AD.
Gorgons were a popular image in Greek mythology, appearing in the earliest of written records of Ancient Greek religious beliefs such as those of Homer, which may date to as early as 1194–1184 BC. Because of their legendary and powerful gaze that could turn one to stone, images of the Gorgons were put upon objects and buildings for protection. An image of a Gorgon holds the primary location at the pediment of the temple at Corfu, which is the oldest stone pediment in Greece, and is dated to c. 600 BC.
The Pantheon was a place of public entertainment on the south side of Oxford Street, London, England. It was designed by James Wyatt and opened in 1772. The main rotunda was one of the largest rooms built in England up to that time and had a central dome somewhat reminiscent of the celebrated Pantheon in Rome. It was built as a set of winter assembly rooms and later briefly converted into a theatre. Before being demolished in 1937, it was a bazaar and a wine merchant's show room for over a hundred years. Marks and Spencer's "Oxford Street Pantheon" branch, at 173 Oxford Street now occupies the site.
Chalcedon originated as a Megarian colony in 685 BCE. The colonists from Megara settled on a site that was viewed in antiquity as so obviously inferior to that visible on the opposite shore of the Bosphorus (with its small settlements of Lygos and Semistra on Seraglio Point), that the 6th-century BCE Persian general Megabazus allegedly remarked that Chalcedon's founders must have been blind. Indeed, Strabo and Pliny relate that the oracle of Apollo told the Athenians and Megarians who founded Byzantium in 657 BCE to build their city "opposite to the blind", and that they interpreted "the blind" to mean Chalcedon, the "City of the Blind".
The Romans were renowned for their architecture, which is grouped with Greek traditions into "Classical architecture". Although there were many differences from Greek architecture, Rome borrowed heavily from Greece in adhering to strict, formulaic building designs and proportions. Aside from two new orders of columns, composite and Tuscan, and from the dome, which was derived from the Etruscan arch, Rome had relatively few architectural innovations until the end of the Republic.
In the 1st century BC, Romans started to use concrete widely. Concrete was invented in the late 3rd century BC. It was a powerful cement derived from pozzolana, and soon supplanted marble as the chief Roman building material and allowed many daring architectural forms. Also in the 1st century BC, Vitruvius wrote "De architectura", possibly the first complete treatise on architecture in history. In the late 1st century BC, Rome also began to use glassblowing soon after its invention in Syria about 50 BC. Mosaics took the Empire by storm after samples were retrieved during Lucius Cornelius Sulla's campaigns in Greece.
The Colosseum or Coliseum ( ), also known as the Flavian Amphitheatre (Latin: "Amphitheatrum Flavium"; Italian: "Anfiteatro Flavio" or "Colosseo" ), is an oval amphitheatre in the centre of the city of Rome, Italy. Built of travertine, tuff, and brick-faced concrete, it is the largest amphitheatre ever built. The Colosseum is situated just east of the Roman Forum. Construction began under the emperor Vespasian in AD 72, and was completed in AD 80 under his successor and heir Titus. Further modifications were made during the reign of Domitian (81–96). These three emperors are known as the Flavian dynasty, and the amphitheatre was named in Latin for its association with their family name "(Flavius)".
The Theatre of Dionysus Eleuthereus is a major theatre in Athens, considered to be the world's first theatre, built at the foot of the Athenian Acropolis. Dedicated to Dionysus, the god of plays and wine (among other things), the theatre could seat as many as 17,000 people with excellent acoustics, making it an ideal location for ancient Athens' biggest theatrical celebration, the Dionysia. It was the first theatre ever built, cut into the southern cliff face of the Acropolis, and supposedly the birthplace of Greek tragedy. The remains of a restored and redesigned Roman version can still be seen at the site today. It is sometimes confused with the later, smaller, and better-preserved Odeon of Herodes Atticus, located nearby on the southwest slope of the Acropolis.
The site has been used as a theatre since the sixth century BC. The existing structure dates back to the fourth century BC but it has had many other later remodellings. 
On November 24, 2009 the Greek government announced that they would partially restore the Theatre of Dionysus.
Modern historians' dates for the war have been hotly debated, with no clear consensus. It is generally accepted that the war lasted 10 years, and ended in summer 346 BC (one of the few firm dates), which yields a date of 356 BC for the beginning of the war, with Philomelos's seizure of Delphi. Diodorus's chronology for the sacred war is very confused—he dates the start and end of the war a year too late, variously says the war lasted 9, 10 or 11 years, and included the siege of Methone twice under different dates—and his dates cannot therefore be relied upon.
Construction of the Colosseum began under the rule of Vespasian in around 70–72 AD (73–75 AD according to some sources) The Colosseum had been completed up to the third story by the time of Vespasian's death in 79. The top level was finished by his son, Titus, in 80, and the inaugural games were held in AD 80 or 81. Dio Cassius recounts that over 9,000 wild animals were killed during the inaugural games of the amphitheatre. Commemorative coinage was issued celebrating the inauguration. The building was remodelled further under Vespasian's younger son, the newly designated Emperor Domitian, who constructed the "hypogeum", a series of underground tunnels used to house animals and slaves. He also added a gallery to the top of the Colosseum to increase its seating capacity.
The only passages referring to the decoration of the Agrippan Pantheon written by an eyewitness are in Pliny's "Natural History". From him we know that "the capitals, too, of the pillars, which were placed by M. Agrippa in the Pantheon, are made of Syracusan bronze", that "the Pantheon of Agrippa has been decorated by Diogenes of Athens, and the Caryatides, by him, which form the columns of that temple, are looked upon as masterpieces of excellence: the same, too, with the statues that are placed upon the roof," and that one of Cleopatra's pearls was cut in half so that each half "might serve as pendants for the ears of Venus, in the Pantheon at Rome".
The establishment of Constantinople served as one of Constantine's most lasting accomplishments, shifting Roman power eastward as the city became a center of Greek culture and Christianity. Numerous churches were built across the city, including the Hagia Sophia which was built during the reign of Justinian the Great and remained the world's largest cathedral for a thousand years. Constantine also undertook a major renovation and expansion of the Hippodrome of Constantinople; accommodating tens of thousands of spectators, the hippodrome became central to civic life and, in the 5th and 6th centuries, the epicenter of episodes of unrest, including the Nika riots. Constantinople's location also ensured its existence would stand the test of time; for many centuries, its walls and seafront protected Europe against invaders from the east and the advance of Islam. During most of the Middle Ages, the latter part of the Byzantine era, Constantinople was the largest and wealthiest city on the European continent and at times the largest in the world.
Darius I built the greatest palace at Persepolis on the western side of platform. This palace was called the "Apadana". The King of Kings used it for official audiences. The work began in 518 BC, and his son, Xerxes I, completed it 30 years later. The palace had a grand hall in the shape of a square, each side long with seventy-two columns, thirteen of which still stand on the enormous platform. Each column is high with a square Taurus (bull) and plinth. The columns carried the weight of the vast and heavy ceiling. The tops of the columns were made from animal sculptures such as two-headed lions, eagles, human beings and cows (cows were symbols of fertility and abundance in ancient Iran). The columns were joined to each other with the help of oak and cedar beams, which were brought from Lebanon. The walls were covered with a layer of mud and stucco to a depth of 5 cm, which was used for bonding, and then covered with the greenish stucco which is found throughout the palaces.
Socrates, believed to have been born in Athens in the 5th century BCE, marks a watershed in ancient Greek philosophy. Athens was a center of learning, with sophists and philosophers traveling from across Greece to teach rhetoric, astronomy, cosmology, geometry, and the like. The great statesman Pericles was closely associated with this new learning and a friend of Anaxagoras, however, and his political opponents struck at him by taking advantage of a conservative reaction against the philosophers; it became a crime to investigate the things above the heavens or below the earth, subjects considered impious. Anaxagoras is said to have been charged and to have fled into exile when Socrates was about twenty years of age. There is a story that Protagoras, too, was forced to flee and that the Athenians burned his books. Socrates, however, is the only subject recorded as charged under this law, convicted, and sentenced to death in 399 BCE (see Trial of Socrates). In the version of his defense speech presented by Plato, he claims that it is the envy he arouses on account of his being a philosopher that will convict him.
The cella of the Parthenon housed the chryselephantine statue of Athena Parthenos sculpted by Phidias and dedicated in 439 or 438 BC. The appearance of this is known from other images. The decorative stonework was originally highly coloured. The temple was dedicated to Athena at that time, though construction continued until almost the beginning of the Peloponnesian War in 432. By the year 438, the sculptural decoration of the Doric metopes on the frieze above the exterior colonnade, and of the Ionic frieze around the upper portion of the walls of the cella, had been completed. In the "opisthodomus" (the back room of the cella) were stored the monetary contributions of the Delian League, of which Athens was the leading member.
The accounts of the construction of the Parthenon make it possible to know that the marble intended for the pediments began to be extracted from the quarries of Mount Pentelikon in 439-438 BC.; sculpture work starting the following year. The accounts also show that excavation and transportation expenses were annual. This could mean that different quarries would have been used each year to obtain the highest possible quality marble The last marble purchases in the quarries are recorded in 434 BC. In the logic of the construction of the building, the sculptures of the pediments had to be installed almost at the very end (before the installation of the roof), probably in 432 BC.
The Old Parthenon was still under construction when the Persians sacked the city in the Destruction of Athens in 480 BC, and razed the acropolis during the Second Persian invasion of Greece. The existence of the proto‐Parthenon and its destruction was known from Herodotus and the drums of its columns were plainly visible built into the curtain wall north of the Erechtheum. Further material evidence of this structure was revealed with the excavations of Panagiotis Kavvadias of 1885-1890. The findings of this dig allowed Wilhelm Dörpfeld, then director of the German Archaeological Institute, to assert that there existed a distinct substructure to the original Parthenon, called Parthenon I by Dörpfeld, not immediately below the present edifice as had been previously assumed. Dörpfeld’s observation was that the three steps of the first Parthenon consist of two steps of "poros" limestone, the same as the foundations, and a top step of Karrha limestone that was covered by the lowest step of the Periclean Parthenon. This platform was smaller and slightly to the north of the final Parthenon, indicating that it was built for a wholly different building, now wholly covered over. This picture was somewhat complicated by the publication of the final report on the 1885–90 excavations indicating that the substructure was contemporary with the Kimonian walls, and implying a later date for the first temple.
If the original Parthenon was indeed destroyed in 480 BC, it invites the question of why the site was left a ruin for 33 years. One argument involves the oath sworn by the Greek allies before the battle of Plataea in 479 BC declaring that the sanctuaries destroyed by the Persians would not be rebuilt, an oath the Athenians were only absolved from with the Peace of Callias in 450. The mundane fact of the cost of reconstructing Athens after the Persian sack is at least as likely a cause. However the excavations of Bert Hodge Hill led him propose the existence of a second Parthenon begun in the period of Kimon after 468 BC. Hill claimed that the Karrha limestone step Dörpfeld took to be the highest of Parthenon I was in fact the lowest of the three steps of Parthenon II whose stylobate dimensions Hill calculated to be 23.51x66.888m.
Church visited Greece in 1869 and spent several weeks in Athens, where he made numerous studies of the ruins of the Parthenon that later served as the basis for the work. In 1871 a commission from the financier and philanthropist Morris K. Jesup finally allowed Church to begin work on his "big Parthenon".