The Old Fort, also called the Arab Fort, is the oldest surviving building in Stone Town. Its battered orange-brown walls form a near-square between Forodhani Gardens and the back lanes of the old town, with crenellations that lean outwards in the Omani fashion. It served at various points as a garrison, a customs post, a women's prison and a railway terminus before being converted in the 1990s into a cultural centre.
The interior is now an open courtyard with a small amphitheatre, used for film screenings during the ZIFF festival each July and for craft markets at other times. There is little to see in the way of exhibits, but the climb up the south tower gives a good early-trip view over the rooftops to orient yourself before you wander into the alleys.