Stone Age people built a lot of tombs or tomblike structures out of gigantic rocks covered with mounds of earth; this building technique makes the tombs look like big, grassy mushrooms from the outside. These ancient tombs continue to intrigue people today; there are so many of them all over the landscape, they're hard to miss.

The megalithic tombs were probably constructed shortly before the arrival of the Celts, who called them fairy mounds and believed that the spirits of ancient people — bold heroes and brave maidens — lived there. The Celtic creator gods, the Tuatha Dé Danann, were known to be fabulously good at building things, and perhaps it was they who constructed the tombs dotting the countryside.

Eventually the spirits inhabiting the fairy mounds transformed into the little people of later Irish legends — leprechauns and fairies and brownies, whose spirits are said to haunt the land.

Passage Tombs

Many of these tombs are called passage tombs because they contain passages leading to burial chambers underneath the mound. The walls of the passage and chamber are made of rock, often elaborately carved.

Court Tombs

Court tombs, or cairns, have an open, roofless courtyard in front leading into two, three, or four chambers at back. Archaeologists have found human remains in them, but think that they might originally have been built as temples. They tend to be evenly distributed about 3 miles apart instead of clustered like graves; generally structures that are spaced like that are places of worship, but there's no way to tell for sure how people used them.

Wedge Tombs

Wedge tombs also occur primarily in the northern part of Ireland. These tombs have stone walls and roofs; the roof gets lower and the passage narrower as one goes into the tomb, hence the name wedge. Most of them face west or southwest, toward the setting sun.

Wedge tombs are numerous; there are about 500 of them all over the northern part of the country. The ones that have been excavated contain human remains, and some contain pottery, which suggests that they were made toward the end of the Neolithic period. Labbacallee (“Hag's Bed”), in County Cork, is an excellent wedge tomb. It got its strange name because it contained the skeleton of a headless woman when it was first opened.

Portal Tombs

Portal tombs, also called dolmens, consist of several large upright stones topped by a giant capstone. Putting these rocks in place must have been a stupendous effort — some capstones weigh as much as 100 tons. These dolmens were originally surrounded by a mound of earth, and people were buried inside them. A giant dolmen at Poulnabrone, County Clare, had more than twenty people buried in it over a 600-year period; this might mean that only royalty was buried there.

There are dolmens all over Ireland, as well as in Wales and Cornwall. The Kilclooney More dolmen in County Donegal is particularly cool — its capstone is almost 14 feet long.