Between 1835 and 1861, Richard Butler wrote four editions of his history of Trim.2 In the 140 years since that time, the publication of a large corpus of primary documents relating to medieval Irish towns has been accompanied by a revolution in approaches to source material and research methodology. More recently, archaeology has come to play a central role as a means of understanding Ireland’s urban past. Large-scale excavations have been carried out in many towns and an Urban Archaeology Survey has been completed. Very little synthesis has been done, however, and where it has, it has been confined to the largest of Ireland’s towns. Consequently, almost nothing is known about the smaller, more typical, market towns of medieval Ireland. The present study is the first major work on Trim since 1861 and is a synthesis of all archaeological and historical information for any medieval Irish town. The principal reasons for selecting Trim are the quality and quantity o f its surviving medieval remains, the availability of a substantial amount of documentation, and the fact that a number of major archaeological excavations have taken place there. This thesis is the result of a multi-disciplinary approach, founded on a systematic analysis of all published and unpublished documents, a thorough review o f the archaeological excavations, and an architectural survey of the town’s upstanding medieval remains.