York's almost 3 miles of ancient stone walls are among the best preserved in England. A walk on the narrow paved path along the top leads you through 1,900 years of history, from the time the earthen ramparts were raised by the Romans and York's Viking kings to repel raiders, to their fortification by the Normans, to their current colorful landscaping by the city council. The walls are crossed periodically by York's distinctive "bars," or fortified gates: the portcullis on Monk's Bar on Goodramgate is still in working order, and Walmgate Bar in the east is the only gate in England with an intact barbican. It also has scars from the cannon balls hurled at it during the Civil War. Bootham Bar in Exhibition Square was the defensive bastion for the north road, and Micklegate Bar, in the city's southwest corner, was traditionally the monarch's entrance. To access the path and the lookout towers, find a staircase at one of the many breaks in the walls.