Hammershus Castle Ruins

Allinge-Sandvig, Denmark

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Hammershus Castle Ruins, located in Allinge-Sandvig on the island of Bornholm, Denmark, is the largest medieval fortress in Northern Europe.

Built around the early 1300s, probably by Archbishop Jens Grand of Lund, it was a strategic stronghold overseeing the Baltic Sea and played a key role in the centuries-long power struggle between the Danish crown and the Catholic Church. The fortress features massive stone walls, a grand tower, and a long perimeter wall that once enclosed residential buildings, a church, granaries, and other facilities.

Throughout its history, Hammershus changed hands multiple times, including being occupied by the Swedes in the 17th century before a local rebellion returned it to Danish control. It was also used as a prison, famously holding Leonora Christine, daughter of King Christian IV. The castle was abandoned in the mid-18th century, with materials removed for other constructions, and declared a national heritage site in 1822.

Today, the ruins are a popular tourist attraction offering panoramic views, well-preserved masonry, and a vivid window into Denmark’s medieval history and political conflicts.​