The Castle of Monção was built by King Denis of Portugal in 1306 and it was enlarged in 1656. From the original castle, the only remains are two doors, some pieces of the medieval wall, and the Torre de Lapela Towers, which shows off the coast of arms of King Ferdinand I.
From the walls, the only remain is the main door, defended by the Keep, with a Gothic style; and the treachery door, with a smaller size. From the 17th century fortress there are many parts still standing, such as the Porta de Salvaterra Door and some bastions.
References:Towering 52 meters above the sea, Bengtskär lighthouse is the tallest one in Scandinavia. The building started in in 1905 after the shipwreck of S/S Helsingfors and was completed in 1906. The lighthouse was designed by architect Florentin Granholm. On December a special petrol lantern, designed and built in Paris, was brought to Bengtskär and installed atop the tower.
German fleet bombarded Bengstkär in the First World War in 1914. Since the Gulf of Finland was heavily mined, it was not until 1919 that the surrounding seas were declared safe for shipping, that the light was lit again.
After the war the military value of Bengtskär increased as part of the defence system of independent Finland. In Second World War (1941) Soviet Union made a suprise attack to island. After a bloody battle, the small Finnish garrison emerged victorious. Intermittent repairs to the facility continued during the post-war period.