York, UK

York, a city of about 210,000 residents on the River Ouse in northern England, was founded as Eboracum by the Romans in 71 AD. Constantine the Great was proclaimed emperor here in 306, and the 1220 York Minster stands as the largest Gothic cathedral in northern Europe, with a Great East Window from 1405 the size of a tennis court. The 3.4-km city walls form the longest medieval walls in England, while the Shambles, recorded in the Domesday Book of 1086, is the best-preserved medieval street in Britain. The 1839 National Railway Museum holds the world's largest collection of locomotives.