In early 1609, building was started on the forts on Bandaneira, after the VOC had resolved to build forts on the Banda Islands to maintain control over the spice trade, on which the VOC claimed a monopoly. Fort Nassau was built on the remains of an earlier fort that the Portuguese had had on Bandaneira. It was a rectangular stone fort, with angled bastions on each corner. Some years later a mote was dug around the fort. In the 18th century a hornwork was added on the seaside. Fort Nassau, situated on the seaside, was the administrative headquarters of Bandaneira. The fort was initially vulnerable from the land side: for this reason a small redoubt was erected on the hill behind the fort in 1611. In the course of the 17th century, this redoubt was expanded to become Fort Belgica. Nassau came to be known as the water fort. Nowadays the western, southern and eastern walls as well as the bastions on the southern side still remain. The northern wall and the two northern bastions were torn down in 1896. In that same period, the mote was filled up and bricks and stones from the fort were used as building materials. Until 2018, the fort was largely overgrown and dilapidated. Since then, however, extensive restorations have taken place.