Forts were ramparts built of clay (raths) and stone (cabers or cashels). They have given their name to many Irish towns, for example Rathdrum, Rathfriland, Cahirsiveen and Cashel . Since there are said to be 40,000 forts it would be hard to miss them. This term was used for any strengthened structure including stockades and cattle enclosures. Staigue Fort in Kerry, Garranes in Cork, Dun Aongahsa

Clare Grianan of Aileach in Donegal and Navan Fort (Eamhain Macha) near Armagh City are among the best. Tara once the palace of the high kings of Ireland, has a number of raths. Ringforts are the most common site type in Ireland. They were primarily built and used during the Early Christian period, 500-1200 AD. They are differentiated from cashels in having enclosing banks composed of dumped earth and sometimes a mixture of earth and stone. However these distinctions are not clear cut and some sites had earthen banks faced with stone, or had sections of the enclosing element composed alternately of earth or stone. In some cases the enclosing element is so eroded or robbed out and sod covered that it can be difficult to determine if it had originally been a wall or bank. The distinctions between ringforts and cashels may be more apparent to archaeologist than the people who built and used the sites and the choice of enclosing a site with stone or earth, or a combination of the two may have been determined by the availability of material, the difficulty of digging a fosse as well as social concerns of status, manpower and legal restraints. Cashels were constructed at the same period and fulfilled the same functions as ringforts. They differ in their construction technique, being assembled rather than quarried and piled up, and therefore usually lack an enclosing fosse. The usual technique was usually to construct two concentric drystone walls of medium-sized blocks and slabs, limestone was the preferred material, set on a foundation of large boulders. The are between was then infilled with rubble. The construction technique allowed for some elaboration and in some case chambers were built into the walls, sometimes linked to souterrains, and stone steps might lead to broad wall walks. The walls are often, when well preserved, 2m or higher. As they represent a ready source of stone may have been plundered to build field walls, roads and houses. The quarrying and or collection of suitable stone, its transport and the requirements for skilled wall builders made a cashel a more expensive alternative to a ringfort and they are much leass common. They are also restricted to areas where suitable stone was available. Individuals unable to construct a complete cashel may have added stone revetments to ringforts to make them resemble cashels. Stone enclosure at Carrigillihy, Co. Cork was found to date to the Early Bronze Age and some cashels appear to have been occupied into the medieval period so that the site type appears to have a long currency.