The dolmen are stone structures around the world that are very identified by large vertically planted stones with a larger stone forming a structual cavity.  Originally it was probably a tomb which was covered with earth to form a mound. It was plundered, eroded and probably used as a quarry for building material over the previous 3000 plus years.  In 1985 some restoration work was done as well as an excavation that found the bodies of 16 to 22 adults and six children under the structure.  The dolman sits on the rocky plateau known as the Burren (Irish: Bioreann, meaning "great rock") has been dated to about 1700 bce. [Wikipedia]