Volume 1 of a new BAR series entitled 'Limina/Limites: Archaeologies, histories, islands and borders in the Mediterranean (365-1556)' which seeks to invite editors of proceedings of conferences and workshops, authors of individual monographs and collective studies which, regardless of their discipline, are targeted at the integration of diverse data sources and systems oriented at a global reconstruction, and geared to long-term trends and to Mediterranean-wide spatial dimensions. This first volume in the 'Limina/Limites' presents the proceedings of the conference 'Transjordan in 12-13th Centuries and the Frontiers of the Medieval Mediterranean', held in Florence between 6-8 November 2008.