The location of Nassau Fortress was obtained from old documents from the Vereenigde Oostindische Compagnie (VOC) era. Based on the sketch of Nassau Fortress Gorontalo, it has several buildings inside, such as a residential building, warehouse, military barracks, gunpowder warehouse, kitchen, employee house and horse stable. The fort was also equipped with two bastions. Front bastion to monitor Gorontalo Bay. Rear bastion to monitor land area.
Based on old documents from the Vereenigde Oostindische Compagnie (VOC), the research team from the North Sulawesi Archeology Center conducted an initial survey in 2009 and started excavation in 2018. Excavations carried out by the North Sulawesi Archeology Center succeeded in finding the structure of a septic tank with a thickness of 30 cm and found indications of the structure.
The discovery of the excavation process was continued to find the fort and bastion structures in order to estimate the size of the fort but until the final process, the fort and bastion structures were not found. The search for the structure was constrained by several buildings located at the excavation site and a new building being built over the fort structure that had been found previously.
The Nassau Fortress in Gorontalo has been destroyed and only the foundation structure remains. The possible cause of the destruction of the fort, due to floods, tsunamis and earthquakes or collapse with age.