a city in north-east England on the River Ouse. It it in the county of North Yorkshire, but has its own unitary authority. It is known especially for its ancient buildings, including York Minster. It was an important city in Roman times and in the Middle Ages, and it was the most important city in the Anglo-Saxon region of Northumbria. The city has many visitors and its attractions include the National Railway Museum and the Jorvik Viking Centre, which has exhibitions about the period when people from Scandinavia invaded Britain.