Hammershus Castle (Hammershus slot)

Hammershus is Scandinavia's largest medieval fortification and one of Denmark's most significant historical sites. Located on the island of Bornholm, the castle was established in the 13th century. It is currently managed by the Danish Ministry of Energy, Utilities, and Climate through the Danish Nature Agency (Naturstyrelsen).

The ruins of Hammershus serve as a massive open-air museum and are free to visit. It was originally built to establish a presence for the Archbishop of Lund and was later a point of contention between the church and the Danish crown. After the abolition of the castle's military function in the 1700s, it fell into disrepair and was used as a source of building material until it was protected as a national monument in 1822.