Søborg Castle

Søborg Castle (Danish: Søborg Slot), in its heyday, was the strongest castle in Denmark, and was also used as a prison (Jens Grand was imprisoned here in the 13th century). It was inhabited until the Count's Feud in 1535, when it is speculated that it was destroyed. In 1577, the feudal tenant was granted permission to use the ruins as a quarry.

• http://en.wikipedia.org/wiki/Søborg Castle