York city walls in the context of York railway station (1841)

York is a cathedral city in North Yorkshire, England, with Roman origins, sited at the confluence of the rivers Ouse and Foss. It has many historic buildings and other structures, such as a minster, castle and city walls, all of which are Grade I listed. It is the largest settlement and the administrative centre of the wider City of York district. It is located 27 miles (43 km) north-east of Leeds, 90 miles (140 km) south of Newcastle upon Tyne and 207 miles (333 km) north of London. York's built-up area had a recorded population of 141,685 at the 2021 census.

The city was founded under the name of Eboracum in AD 71. It then became the capital of Britannia Inferior, a province of the Roman Empire, and was later the capital of the kingdoms of Deira, Northumbria and Scandinavian York. In the Middle Ages it became the northern England ecclesiastical province's centre, and grew as a wool-trading centre. In the 19th century it became a major railway network hub and confectionery-manufacturing centre. In the Second World War York was bombed in the Baedeker Blitz. Although York was less targeted during the war than other, more industrialised northern cities, several historic buildings were gutted and restoration took place up until the 1960s.

Defensive walls are a feature of ancient Roman architecture. The Romans generally fortified cities, rather than building stand-alone fortresses, but there are some fortified camps, such as the Saxon Shore forts like Porchester Castle in England. City walls were already significant in Etruscan architecture, and in the struggle for control of Italy under the early Republic many more were built, using different techniques. These included tightly fitting massive irregular polygonal blocks, shaped to fit exactly in a way reminiscent of later Inca work. The Romans called a simple rampart wall an agger; at this date great height was not necessary. The Servian Wall around Rome was an ambitious project of the early 4th century BC. The wall was up to 10 metres (32.8 ft) in height in places, 3.6 metres (12 ft) wide at its base, 11 km (7 mi) long, and is believed to have had 16 main gates, though many of these are mentioned only from writings, with no other known remains. Some of it had a fossa or ditch in front, and an agger behind, and it was enough to deter Hannibal. Later the Aurelian Wall replaced it, enclosing an expanded city, and using more sophisticated designs, with small forts at intervals.

The Romans walled major cities and towns in areas they saw as vulnerable, and parts of many walls remain incorporated in later defences, as at Córdoba (2nd century BC), Chester (earth and wood in the 70s AD, stone from c. 100), and York (from 70s AD). Strategic walls defending the frontiers of the Empire by running across open country were far rarer, and Hadrian's Wall (from 122) and the Antonine Wall (from 142, abandoned only 8 years after completion) are the most significant examples, both on the Pictish frontier. Most defences of the borders of the Roman Empire relied on systems of forts and roads without attempting a continuous barrier.