The Ruhnu wooden church, built in 1644, is the oldest known wooden building in Estonia. The church's baroque-style tower was finished in 1755. The oldest parts of the building are the polygonal choir and altar, and the nave. The altar is covered with a thin, polished stone slate; the oaken frame stands on sand and is open towards the south.
The stone Lutheran church next to the wooden one was built in 1912 and is currently where services are held.
Bouillon Castle was mentioned first in 988, but there has been a castle on the same site for a much longer time. The castle is situated on a rocky spur of land within a sharp bend of the Semois River.
In 1082, Bouillon Castle was inherited by Godfrey of Bouillon, who sold it to Otbert, Bishop of Liège in order to finance the First Crusade. The castle was later fitted for heavy artillery by Vauban, Louis XIV's military architect in the late 17th century.
The castle is entered over three drawbridges. The main courtyard then leads to the ducal palace with its 13th century Salle Godefroy de Bouillon. From there visitors climb up to the top of the 16th century Tour d’Autriche for a breathtaking panorama of the town and river, before they way back via the torture chamber, citerns and dungeons, and past the 65m deep well Shaft.