The 36-meter Kõpu lighthouse, in the western part of Estonia's second-largest island, was built in the beginning of the 16th century. According to historical records, the first firewood was ignited at the top of the lighthouse on August 1, 1531. The tower served as an important beacon for merchant fleets of the Hanseatic League that were sailing in the Baltic.
The lens still in use, floating in a mercury basin, was bought from a Paris exhibition in 1901. Kõpu lighthouse is visited by nearly 30,000 tourists every year. Hiiumaa's Kõpu, Ristna and Tahkuna are the only Estonian lighthouses regularly open for public visitation.