Barrows have been constructed in Ireland since the Middle Neolithic and were in use until the early centuries A.D. They may cover or contain megalithic Linkardstown type cists of the Neolithic, all of the burials type of the Bronze Age (see below) or cremations or inhumations of the Iron Age. In the east of Ireland the mounds of these these sites have been levelled in large numbers, leaving Ring-ditches, or have been remodelled into ceremonial enclosures, as at Tara   , or Medieval Mottes as at Rathmore, Co. Kildare. In the east Ring-ditches have been dates as late as the seventh century AD. Bowl Barrows, often referred to as Tumuli or Moats, have a central dome-shaped mound, 2m or higher, usually enclosed by a fosse and one or more external banks. Where an enclosing fosse is not noted on the ground it is often found during excavation. Saucer barrows have low mounds, usually under 1m, and range from 5-20m in diameter with one or more enclosing fosses and banks. Bell barrows resemble bowls but have a berm between the mound and the fosse. Ring Barrows resemble Saucer barrows but have a flat interior rather than a mound. Another type of barrow has a bank and a hollow interior, these are pond barrows. Excavation has revealed that a significant number of barrows belong to the Iron Age (c. 300 BC-100 A.D), but many are of Bronze Age date as well. The barrows are often found in groups or cemeteries where a number of types can be found together. Sometimes they are found juxtaposed to megalithic cemeteries as at Carrowmore, Co. Sligo or associated with ceremonial enclosures.