Otanaha Fortress sits on a hill above Lake Limboto, reached by a long stairway that is as much part of the visit as the stone walls at the top. The fort is modest, but the view over Gorontalo, the lake, and the surrounding hills is the best in the area.
Local tradition connects the fort to old Gorontalo kingdoms and Portuguese contact, though the exact history is more tangled than the signs suggest. Go for the setting and the sense of Gorontalo's inland geography opening below you.