Roskilde Cathedral

Roskilde cathedral is a very nice cathedral which is the burial ground for danish monarchs. The cathedral is listed as an UNESCO World Heritage Site. The cathedral was built in the 12th and 13th centuries, and it was Scandinavia's first Gothic cathedral to be built of brick.
At the entrance I got a information sheet about the cathedral, they even had on in dutch :) I walked around and saw al the different porches and side chapels. There are many tombs and crypts spread over the cathedral.
If I remember right there also was the possibility of a guided tour at certain times.