At its height, the Roman Empire was the greatest empire yet seen, its borders stretching from the rain-swept highlands of Scotland in the north to the sun-scorched Nubian desert in the south. But how were the vast and varied stretches of frontier defined and defended? Many of Rome's frontier defenses have been the subject of detailed and ongoing study and scholarship. Three frontier zones are now UNESCO World Heritage sites (the Antonine Wall having recently been granted this status - the author led the bid), and there is growing interest in their study. This wide-ranging survey will describe...