This is one of the great sacred landscapes of the ancient world. At the center of the Coolera Peninsula sits a massive passage grave that once had a Stonehenge-like stone circle of its own. Encircling that were as many as 200 additional stone circles and passage graves arranged in an intricate and mysterious design. Over the years, some of the stones have been moved; more than 60 circles and passage graves still exist, although the site spreads out so far that many of them are in adjacent farmland. Look for your first dolmen in a paddock next to the road about a mile before you reach the site. The dolmens were the actual graves, once covered in stones and earth. Some of these sites are open to visitors, and you can get a map to them from the visitor center. (Not all are, however; be careful not to trespass on private land). On the main site, the oldest tomb is thought to date from around 3,700 b.c.—making it one of the oldest pieces of freestanding stone architecture in the world. From Carrowmore, you can see the hilltop cairn grave of Knocknarea, which is about 4km (2 1/2 miles) away. The visitor center has good exhibits and guided tours. Follow signs from Woodville Road heading west out of Sligo Town, or from R292 at Ransboro.