and covered with earth or other, smaller stones. They are a type of chamber tomb, and the term is used to describe the structures built across Atlantic Europe, the Mediterranean, and neighbouring regions, mostly during the Neolithic period, by Neolithic farming communities. They differ from the contemporary long barrows through their structural use of stone. There is a huge variety of megalithic tombs. The free-standing single chamber dolmens and portal dolmens found in Brittany, Denmark, Germany, Ireland, Netherlands, Sweden, Wales, and elsewhere consist of a large flat stone supported by three, four, or more standing stones. They were covered by a stone cairn or earth barrow. In Italy, dolmens can be found especially in Sardinia. There are more than 100 dolmen dating to the Neolithic (3500–2700 BC) and the most famous is called Dolmen di Sa Coveccada (near Mores). During the Bronze Age, the Nuragic civilization built c. 800 Giants' grave, a type of megalithic gallery grave that can be found throughout Sardinia with different structures. The earliest megalithic tombs in Sardinia are the circular graves of the so-called Arzachena culture, also found in Corsica, southern France and eastern Spain. Dolmens are also in Apulia and in Sicily. In this latter region, they are small structures located in Mura Pregne (Palermo), Sciacca (Agrigento), Monte Bubbonia (Caltanissetta), Butera (Caltanissetta), Cava Lazzaro (Siracusa), Cava dei Servi (Ragusa), Avola (Siracusa), and Argimusco in Montalbano Elicona (Messina). Dating to the Early Bronze Age (2200–1800 BC), the prehistoric Sicilian buildings were covered by a circular mound of earth. In the dolmen of Cava dei Servi, archaeologists found numerous human bone fragments and some splinters of Castelluccian ceramics (Early Bronze Age) which confirmed the burial purpose of the artefact. Examples with outer areas, not used for burial, are also known. The Court Cairns of southwest Scotland and northern Ireland, the Severn-Cotswold tombs of southwest England and the transepted gallery graves of the Loire region in France share many internal features, although the links between them are not yet fully understood. That they often have antechambers or forecourts is thought to imply a desire on the part of the builders to emphasize a special ritual or physical separation of the dead from the living. Megalithic tombs appear to have been used by communities for the long-term deposition of the remains of their dead, and some seem to have undergone alteration and enlargement. The organization and effort required