York's city walls — known locally as the Bar Walls — stretch for about 3.4 kilometres around the old city centre and are the longest intact medieval city walls in England. They were built up over many centuries on foundations laid by the Romans, reinforced by the Vikings, and largely given their current form by the Normans and Plantagenets. Walking the full circuit takes about an hour at a leisurely pace and provides a quite different perspective on the city: from the walls you see over rooftops and into gardens, and the relationship between the medieval gates, the Minster, and the river makes more sense than it does from street level.
Four medieval gateways survive — Bootham Bar to the north, Monk Bar to the northeast, Walmgate Bar to the southeast, and Micklegate Bar to the southwest. Each has its own character and history. The walk is free and open at all hours; the steps up to the wall-top are steep in places, and parts close briefly each winter for maintenance. There is no better free orientation to the city.