The earliest fortifications in Pillau were made in 1550, when it was an important port of the Duchy of Prussia. During the Thirty Years' War, the Swedes occupied the harbour in the aftermath of their victory over the Polish-Lithuanian Commonwealth. King Gustavus Adolphus landed there with his reinforcements in May 1626. After the ceasefire of Altmark (1629) the Swedes retained Pillau and set out upgrading its fortifications. They constructed a star fort which remains one of the town's landmarks. The final completion of the fortress was made by Prussians in 1670.
In June 1807 Pillau was stormed by Napoleon's Grand Army. No outstanding events took place during the rest of the 19th century. Records of a Scottish 'Colony' established here in 1815 appeared in a 1890 Publication, although their authenticity is questionable.
The lighthouse was built up to a height of 31 meters, and the entire fortress was updated and rebuilt by the Prussians in 1871. Currently it is holding a naval museum.
The Gravensteen is a castle in Ghent originating from the Middle Ages. The name means 'castle of the counts' in Dutch. Arnulf I (918–965), Count of Flanders, was the first to fortify this place, building a medieval bastion on this high sand dune, naturally protected by the river Leie and its marshy banks. This bastion consisted of a central wooden building and several surrounding buildings, also in wood.
In the early 11th century, the wooden building was replaced by a stone residence, consisting of three large halls that made up three storeys, connected by a stone stairwell. The monumental stone staircase, the light openings, the fireplaces built into the walls and the latrines were signs of considerable luxury and comfort in those days. There was probably also a tower.