The Sandomierz Royal Castle was built on a slope of Vistula River by Casimir III the Great and extended in the 16th century. The original building was blown up in 1656, leaving only the west wing standing. It was later transformed into a Renaissance styled residence with the west wing preserved as a museum.
The 14th-century castle was built on the site of the existing stronghold in the 10th century. Between 1146-1166 it was the seat of Prince Henry of Sandomierz, son of Bolesław III Wrymouth. The Gothic castle was built by Casimir the Great. The remnants of the Gothic structure are visible in the foundations of the octagonal tower of the south corner, which is the oldest part of the monument. The existing tower was built during the reign of Casimir IV Jagiellon in the 15th century as an integral part of the so-called Great House, the seat of the prince.
During the reign of Sigismund I the Old and Sigismund II Augustus, the castle was enlarged. The Sigismund the Old's cornerstone preserved above the entrance on the east side of the array. It bears the date 1520 and a cartouche with Sigismund's eagle. The construction was supervised by the Royal architect Benedyct Sandomierski, who erected two-storey arcaded cloisters around a closed courtyard.
During the Deluge the castle was blown up by the retreating Swedish troops of general Sincler. About fifty Poles, who entered the abandoned castle, were killed. The survived western wing of the castle was later rebuilt during the reign of king John III Sobieski between 1680-1688.
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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.