The Portal Dolmen is made from large undressed slabs of stone. Two big ones stand face to face, forming a doorway into the tomb. Portal means doorway, and these stones are called the portal stones. Behind this, smaller slabs are placed in a ring to form the walls of a chamber. A giant capstone is placed on top, supported at the front by the portal stones and at the back by one or more of the stones around the chamber. The capstone generally slopes at an angle of about 30 degrees.
The remains of the dead person was placed in the chamber and a flat stone was placed between the portal stones to block up the doorway.
In the past archaeologists thought that the entire dolmen was then covered with a clay mound, as in other types of Neolithic tomb, but it is now thought that this did not occur. A low mound may have been built around the base, up to a height of a few feet.