This volume explores how and why people built enclosures in European prehistory, from their first appearance in the Neolithic to the creation of elaborate fortifications in the Iron Age. The articles here originated as a session at the Seventh Annual Meeting of the European Association of Archaeologists, in 2001, and are written by well-known prehistorians from around Europe. They bring new evidence from new discoveries, and new ideas about old discoveries, to a wider discussion of issues that affect archaeologists of all periods.