Numerous prehistoric sites, dating from the Stone and Bronze Ages, dot the landscape of the
Burren. This is the famous Poulnabrone dolmen, a classic example of a megalithic portal tomb,
with two tall portal stones flanking the entrance to a rectangular stone-lined chamber, covered
with a single large capstone. Excavations have revealed the remains of at least 33 individuals
buried in the chamber some time around 3000 B.C.

There are similar dolmens to be seen in Wales, also: http://www.pbase.com/chrisg_62/image/130127051