St. Olaf's Church in Hullo is the main building of the island and the reason most visitors come ashore. The stone church dates from the 14th century, rebuilt and patched over the centuries, with a wooden bell tower added in the 18th. The interior is plain — a Lutheran whitewash over older Catholic walls — and the acoustics for the occasional summer concert are surprisingly good.
The graveyard around the church is the real reason to stop. Almost three hundred stone wheel crosses, carved between the 17th and early 20th centuries, lean and tilt at every angle among the long grass. The design — a cross within a circle, often with a hole in the centre — is unique to the island's Estonian Swedish community.