The first fort (Fort George) was built between 1760 and 1763, the second (Fort Wilhelm) in 1774, a third in 1784, and the last (called Fort Luise) was built in 1806.
Esimene kindlus (Fort Georg) ehitati aastatel 1760 kuni 1763, teine (Fort Wilhelm) 1774. aastal, kolmas 1784. aastal ja viimane (Fort Luise) ehitati 1806. aastal.