Carmarthen Castle was one of the largest castles in medieval Wales. It was also one of the most important, in its role as a centre of government and as a Crown possession in a region dominated by Welsh lands and Marcher lordships. Largely demolished during the seventeenth century, it was subsequently redeveloped, first as a prison and later as the local authority headquarters. Yet the surviving remains, and their situation, are still impressive. The situation changed with a major programme of archaeological and research work, from 1993 to 2006, which is described in this book. The history of t