Montemolín was inhabited long before our era and received the influence of Lusitanians, Beturians, Celts and the Turduli. During the Arab domination, it was also an important enclave strategically located on the border between Andalusia and Extremadura, with a powerful fortress for defense.
Although there is no record of the beginning of the fortress's construction, it may have been erected around the 12th century. The earliest known information about the fortress dates back to the year 1246 when the castle was reconquered and handed over to the Military Order of Santiago.
The walls of the fortified enclosure cover a significant length, surrounding the hill's summit that dominates the town and offers a clear view over long distances. These walls are made of rammed earth with attached prismatic towers that punctuate the perimeter. The shape is similar to a rectangle about 130 meters long and 50 meters wide, adapted to the natural defensive terrain. The foundations are sometimes made of masonry. In the southeastern flank, the remains of a barbican to protect the main gate are preserved, along with two attached towers, which were typical features of Arab fortresses. The entrance arch, made of brick and over three meters thick, is framed between two octagonal towers, projecting outward and chamfered or octagonal in profile, following a design tradition borrowed from Roman and Byzantine constructions. From the main enclosure, only remnants of seven solid corner towers remain, two of which are covered, and the other five are freestanding. There are two major towers: the Miramontes Tower and the Homage Tower.
During the possession of the castle by the Order of Santiago, very few maintenance and restoration works were carried out.
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.