The Norman defences of York existed largely as earthen banks topped with a wooden palisade, but there were stone gateways, of which three survive.
Bootham Bar is on the site of the north-west gate of the Roman fortress. The outer arch is probably late 11th century, while the inner arch has features which suggest a date in the mid 12th century. The gate was heightened in the 14th century.
Micklegate Bar was the principal south-western entrance to the medieval city. The outer arch and the walling of the gate passage are probably early 12th century. The upper storeys are 14th century.
Walmgate Bar formed the entrance to the Walmgate suburb on the south-east side of the city, first defended in the 12th century. This is the date of the outer arch of the gate. The upper parts of the gate and its barbican are 14th century and later.
Pevsner, D. and Neave, D., 1995. The Buildings of England, Yorkshire: York and the East Riding (London, Penguin), 192-4
Royal Commission on Historical Monuments (England), 1972. An Inventory of the Historical Monuments in the City of York. 2: The Defences (London, HMSO)