"De Burcht" is the typical example of a Shell Keep. Located in the centre of Leiden on a 9 meter high hill, at the point where two arms of the river Rhine come together. Archeological research shows wooden buildings on this spot around the year 1000 AD. The Keep was buld in stone for sure since 1203. It has been rebuild several times since. There is mentioning of a tower in the 14th and 15th century, it's use however unknown. Because of more and more buildings, the Keep lost it's military use. In 1651 a new entrance was build on the south side.
The Keep is a monument and open all year for visitors. Entrance is free.