Castle of Hasznos, Medieval castle ruins in Hasznos, Hungary.

The ruins of Castle of Hasznos stand on a 383 m rocky peak above the Hasznosi reservoir, not above the Kövecses stream. The castle was divided into a lower and an upper ward separated by a dry ditch. Today only parts of the palace walls and the foundations of a square tower remain, with two higher wall fragments rising above the vegetation.

The fortress began in the 14th century when the noble Rátót family built it as a regional military stronghold. It appears in old records under the name Castellanus de Hasnos and served to control the area during the medieval period.

The name Hasznos survives in the fossil Democricetodon hasznosensis, a hamster species described from teeth and bones found in the diatomite on the hill's eastern side, alongside turtle shells and deer teeth. The 3-hectare hilltop is a natural rock garden where violets, thyme and yellow houseleek flower from early spring to late autumn.

You can reach the ruins by a short walk from the nearby village, following clear paths that lead upward to the site. The walk is manageable and the hilltop location makes it easy to spot from the surrounding area.

The light-coloured diatomaceous earth on the eastern side of Várhegy has yielded turtle shell plates, teeth of an ancient deer, bones of shrews and dormice, and the molar of a fossil hamster. Among these finds was a hamster species new to science, named Democricetodon hasznosensis after the site.