Haapsalu's most fascinating historic sight is the late 13th-century castle that lords over the centre of town. It served as both a religious outpost and military fortress when Haapsalu was the centre of the Saare-Lääne diocese, and managed to survive centuries of war and invasion until Peter the Great finally had it pulled down in 1715. Now its park-like courtyard acts as both a concert venue and a favourite place for locals to stroll. For a supposed ruin, it's surprisingly intact - most of the outer walls and a good part of the main structure are still standing. In summer a café sets up shop here, and visitors can climb the clock tower for a bird’s-eye look at the town. The castle also has its own small museum, which offers the best way to get a look inside the beautiful Dome Church (see below). In addition to the museum, you can explore the underground passage ways and cellars, which are now open to the public for the first time since the 17th-century. Explore the castle grounds outside the church and you can hear the ghostly singing of the White Lady who was supposedly immured here. It’s really just a recording, but don’t tell anyone. This year also saw the opening of a children's park at one end of the moat and several areas to sit and ponder what it must have been like in the days of yore.

Castle grounds open 07:00 - 24:00 (admission free), museum, cathedral and watchtower open 10:00 - 18:00 (admission €3).