St Michael's is the oldest of Šibenik's four fortresses, sitting directly above the old town on a limestone outcrop. A walk up through the lanes from the cathedral takes about ten minutes and ends at a stone stage facing the islands, with views down over the orange roofs and out across the channel to the Šibenik Bridge.
A thorough restoration in 2014 turned the interior into a proper open-air venue and added a small exhibition on the town's medieval history. Concerts run through summer; outside performance evenings you can simply pay the entrance fee and have the whole thing largely to yourself. Sunset is the time to come, with a glass of something from the bar at the top.