Many later bridges had a reinforced concrete core clad in stonework or brick. Others were of brick or local rubble stonework. The project included cleaning, repairing and repointing the monument's exterior and interior stonework. Subterranean portions of the palace feature barrel vaulted stonework. Mainly used to create fire, bow-drills were also used in ancient woodwork, stonework, and dentistry. All the stonework was of Aberdeen granite. The decorative stonework was originally highly colored. It is built in rectangular order and has an interesting stonework on its south walls. The temple base is made out of whitewashed, mud-covered stonework. This aspect of Greek stonework is described as polychrome. Catherine had emblems of her love and grief carved into the stonework of her buildings. Archaeological excavations have recovered significant works in pottery, stonework and gold. The original stonework was used to clad a new concrete structure. Cleaning of the exterior stonework was completed in 2010. The builders also left inscriptions on the stonework conveying various messages and instructions.