York, England
The city was founded in AD 71, when the Ninth Legion conquered the Brigantes and constructed a wooden military fortress on flat ground above the River Ouse close to its confluence with the River Foss. The fortress, which was later rebuilt in stone, covered an area of 50 acres (20 ha) and was inhabited by 6,000 soldiers. The site of the Roman fortress lies under the foundations of York Minster, and excavations in the undercroft have revealed some of the original walls.
Roman Emperor Constantine the Great proclaimed Emperor at York in AD 306.