This is really known as the Troldstuerne and signposted and described as such. See also Julian Cope's Megalithic European.
Now, this is a lovely site. It is a double passage grave and the chambers share a wall. It is quite popular. It is near road 21 from Holbæk to Sjællands Odde and signposted from there. Good parking place available but it can be crowded.
Something is not right. This message is just to keep things from messing up down the road