Portal tombs (often referred to as dolmens) are mainly located in the northern half of the country. Such tombs have a straight sided chamber often narrowed at the rear. The entrance is marked by tall portal stones. On top lies a huge single cap stone resting on the portal stones on the front and sloping at the rear where it rests on the backstone. In the majority of cases the tomb entrance faces the east towards the sunrise. This is not always the case though as many tombs face different directions. Examples of portal tombs include Kilmogue, County Kilkenny; Poulnabrone in the Burren, County Clare; and Knockeen, County Waterford.