One of Åland’s premier sights is this striking 14th-century castle on a picturesque inlet (signposted off Rd 2). The keep towers are 15m high in parts, with walls of 3m-thick red granite; it’s easy to see how it would once have ruled over Åland. Exhibits showcase the castle’s evolution and archaeological finds, including a medieval silver-coin hoard. English-language tours (included in admission) depart at 2pm Saturday and Sunday from June to early August and last around 45 minutes.

　　Several extensions, most notably by Gustav Wasa, followed the castle's initial construction. Mad king Eric XIV, deposed by an uprising in 1569, was moved from prison to prison around the Swedish kingdom. He spent three months here, shut up (according to tradition, at least) in a tiny chamber in the Kuretorn keep. A fire in 1745 reduced the castle to ruins; only the northern wing survived.