A Crusader castle on a rock-cut promontory above Wadi Musa, perched at the edge of a sheer drop and reached by a stone bridge over a narrow ravine. Built by King Baldwin I as part of his lordship of Transjordan, it commanded the trade route from Damascus to the Red Sea and the approach to Petra.
What remains is partly ruined — a few walls, a chapel apse, traces of the curtain — but the setting is the thing. From the keep you look straight down into a slot canyon and across at the back of the Petra ridge. Free to visit, signposted from the road below the Mövenpick hotel; about a 20-minute walk in.