Satellite map of Trelleborg (Slagelse)
The Trelleborg (or Trælleborg) west of Slagelse on the Danish island of Zealand, is one of seven Viking ring castles discovered as per 2014. In its day, the fortress was situated on a peninsula that jutted into the swampy area between two rivers. The swamp was connected to the Great Belt by a lake that at its time could be navigated by Viking ships.
Latitude: 55° 23' 23.39" N
Longitude: 11° 15' 33.00" E