In megalithic archaeology a port-hole slab is the name of an orthostat with a hole in it sometimes found forming the entrance to a chamber tomb. The hole is usually circular but square examples or those made from two adjoining slabs each with a notch cut in it are known. They are common in the gallery graves of the Seine-Oise-Marne culture. Text en: Megalithic archeology#Port-hole slab, que redirigeix a: port-hole slab.
