Majestic Kuressaare Castle stands facing the sea at the southern end of the town, on an artificial island defended by stone-faced earth bastions and ringed by a moat. It’s the best-preserved castle in the Baltic and the region’s only medieval stone castle that has remained intact. The castle grounds are open to the public at all times but to visit the keep you'll need to buy a ticket to the castle's branch of the Saaremaa Museum.
A castle was founded in the 1260s, but the mighty dolomite fortress that stands today was not built until the 14th century, with some protective walls added between the 15th and 18th centuries. It was designed as an administrative centre as well as a stronghold. The more slender of its two tall corner towers, Pikk Hermann to the east, is separated from the rest of the castle by a shaft crossed only by a drawbridge, so it could function as a last refuge in times of attack.
Outdoor concerts are held in the castle yard throughout the summer and you can also try your hand at archery. There’s a memorial on the eastern wall to 90 people killed within the castle grounds by the Red Army in 1941. Its grim companion piece lies beyond the castle wall on one of the island ramparts – a large memorial to 300 people executed during the Nazi occupation.
The shady park around the castle moat was laid out in 1861 and there are some fine wooden resort buildings in and around it, notably the Spa Hall (Kuursaal) dating from 1899, which is now a restaurant, and the neighbouring bandstand from 1920. If the weather’s nice, you can hire rowboats (per hour €10) or bikes (per hour €4) from the Spa Hall.