Forte Mare sits where the old town meets the sea, a stubby fortress built directly on the rocks of the shoreline. It has been knocked down and rebuilt by successive owners — Bosnians, Ottomans, Venetians, Austrians — and the patchwork of stonework reflects that.
Inside there is a small exhibition on the fortress's history, but most visitors come for the rooftop terrace, which doubles as an open-air cinema in July and August. The walls drop straight into the water, so the views across the bay are uninterrupted. Combined ticket with the Kanli Kula is good value.