Bolders were used partially underground to create chambers . Therefore also called chamber graves. A huge semi square , somewhat flat bolder was laid on top , for cover , giving it a mushroom-like appearance .
In Mecklenburg and Pomerania large numbers of these graves were disturbed , when towns and cities were built . The bolders came in handy for construction and road building .
There are still many left today , even with the extreme density of population in Germany and all over Europe . An list of hunebeds (Huenenbetten) in northern Germany, made in earlier years by a landowner in Mecklenburg , showed over 1000 hunebeds at that time. I believe that was on Ruegen? , an island in the Baltic Sea , off northern Germany.