Mottes are flat-topped earthen mounds with a fosse at the base. Some, but not all sites. The Motte at Greenmount, Co. Louth, have a sub-rectangular area enclosed by a bank and fosse, known as a bailey, contiguous to the fosse. They were usually constructed at strategic locations, river crossings or on important routeways. Sometimes the builders used pre-existing ringforts and even burial mounds as the bases of these sites. The sites were constructed by Anglo-Norman lords at an early stage of the Norman conquest in the thirteenth century. Today they appear as earthworks but they would originally have been topped woth timber pallisades and are sometimes referred to as timber castles. Most of the examples are found in the east of Ireland, but there are also examples in the west.