Orange Fortress is one of the Portuguese heritage forts. On the inside of the fort there is a rectangular building resembling a cubicle in which there is a room, measuring 4.50 m long, 5.10 m wide, and 1.70 m high. The building is thought to function as a place to store valuables/objects. Apart from being a defensive fortress, Orange Fortress is also equipped with tower support facilities.
In the middle of 15-16 AD, western nations began to come to Indonesia, including the Portuguese. The Portuguese succeeded in occupying the Maluku-Ternate Islands, then to Gorontalo via Kwandang. The desire of the Portuguese to control the Gorontalo area and defend it from attacks by Filipino pirates, especially on the north coast of Kwandang was anticipated by building the Orange Fortress around 1526. Initially, the name of this fort was called OTA, then the Dutch changed its name to Orange Fortress. This fort functioned as a defense base on land and at sea.