A dolmen (stendysse) is a type of single-chamber megalithic tomb, usually consisting of three or more upright stones supporting a large flat horizontal capstone (table). Most date from the early Neolithic period (4000 to 3000 BC). Dolmens were usually covered with earth or smaller stones to form a barrow though in many cases that covering has weathered away, leaving only the stone "skeleton" of the burial mound intact.

Denmark has a large number of Dolmens (Cromlech), Stone circles and other Megalithic sites. Today 2500 Dolmens remain from an estimated number of 25.000.

Poskær Stenhus is from around 3.300 BC and is the largest round barrow in Denmark. The circle of the 23 giant 5 tons heavy stones is 20 meter in diameter.  One stone is missing. This no. 24 stone was removed by a stone cutter in the 1890s who had bought it all to cut  into pieces. Fortunately the local parish executive officer found out and stopped him.

The large cap-stone weighs around 12 tons. It is believed that all the stones have been transported from the beach of Knebel bay 2 km west of the place. The cap-stone is a twin stone. The other part of it which is 19 tons has been used for another dolmen 2 km from Poskær.