Päijälä hill fort is an Iron Age hill fort by the Lake Saaresjärvi in Kuhmoinen. The abundance of artefacts found at the Päijälä hill fort makes it nationally significant. The fort is thought to have been used since at least the 12th century. Kuhmoinen was then a borderland between Häme and Carelian tribes who fought over the ownership of wilderness areas.
The fort hill rises 25 metres above the surrounding terrain, and looking from above you can see the fort is built in a roughly circular form. The slopes of the hill are extremely steep from three sides.
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.