This tower was erected in 1877,and surprisingly, the venerable (respected because of age, distinguished) metal tower is still in good working order. There's a rumor is Gustave Eiffel himself was behind its construction, and but alas,there is no actual proof to confirm this.
The Ruhnu lighthouse is the final of its type left in the Baltic Sea region. The slender central tower is reinforced with four metal counterforts that give the whole building a unique look. The tower stands approximately 130 feet tall.
The building was ordered from Forges et Chantiers de la Méditerranée, a company based in Le Havre, or France. Some parts of the lighthouse complex were damaged during World War I and the building was reconstructed in 1937. It has been working since then and during summer months,it's possible to visit the lighthouse.
Source: atlasobscura.com