A megalith is a large stone or group of stones erected to form a monument, often for ceremonial purposes or to mark a tomb. A stone circle is a distinctive circular arrangement of megalithic stones. Examples of both can be found all over Ireland, probably dating from several thousand years ago. A set of megaliths can be viewed at Ballygroll in County Derry, including free standing stones, several tombs and a stone circle. Kealkil in Count Cork has a well-preserved example of a stone circle with very tall standing stones.
Ancient fortifications range from primitive earthworks, to hill forts, to castles often now in a state of ruin. Henges are even simpler circular earthworks, the purpose of which remains unclear but was possibly ceremonial. Eamhain Mhaca is a complex and well-preserved example of a hill fort located at Navan Fort in County Armagh. Among the more dramatic castle ruins are Puck's Castle in County Dublin, the so-called Rock of Dunamase in Count Laois and those found at Ballymoon and Ballyloughlan in County Carlow. The Longstone Rath at Forenaghts Great in County Kildare has eight-foot high earth banks and a single, tall standing stone.
Barrows or burial mounds are graves covered by mounds of earth and rocks. These can be small and hard to identify, but there are barrows grouped to form a cemetery at Mount Oriel in County Meath, Little Curragh in County Kildare and elsewhere. Cairns are large piles of stones usually signifying a grave. Again there are many examples, such as Crookan Cairn at Knockanvinidee in County Dublin.
Ancient crosses can be found in many locations on the country roads of Ireland. Very early churches can still be viewed, some well-preserved and some in ruins. Cormac's Chapel is a highly decorated 12th century church on the Rock of Cashel in Tipperary County. Aghowle Lower church in County Wicklow is a dramatic example of a ruined church, the only surviving remnant of a monastery founded in the sixth century.
