Tsikhisdziri is home to an archaeological site and ruins of a Late Antique fortified town, which is identified with the Roman-built city-fortress of Petra.
Petra, founded at the behest of the emperor Justinian I in 535 and, after a series of battles for the possession of that city during the Lazic War with Sasanid Iran, was demolished by the Romans themselves to prevent it again becoming the enemy's target in 551. Later, the locale continued to be home to a stronghold of some importance.
The Tsikhisdziri fortress was situated on two coastal hills, connected to each other through double walls. On the territory of the citadel, the area of which totals around 1.5 h, are the ruins of a 6th-century three-nave basilica with the dimensions of 33X17.80 m, with narthex, projecting apse, and floor mosaic, and remains of two other churches, one from the early Christian period and the other dated to the High Middle Ages. Close to the basilica is a 6th-century bath and a water cistern. North to the citadel are the ruins of an urban settlement and hundreds of burials. These structures date from the Late Antiquity to the Middle Ages.
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.