The ruined citadel crowning Citadel Hill (Dealul Cetății, 371 m) was first built in the thirteenth century to resist Mongol incursions, on earlier Roman foundations. It changed hands repeatedly through the centuries — Hungarian, Ottoman, and Habsburg — and was finally blown up in 1849 when the powder magazine caught fire during a siege. The ruins are striking precisely because of their incompleteness: broken towers and crumbled walls set against a sky that drops down to the Mureș valley below.
The hill itself is a protected nature reserve, notable for its rare flora and for the presence of the nose-horned viper (Vipera ammodytes). A funicular runs from the town centre to the top; it is the easier option but the path up through the reserve is worth taking at least one way.