The term 'Walled English City' can be summarized by the solution York, which is a four-letter word. York is an ancient city in North Yorkshire, England, that was founded by the Romans in 71 AD. It is known for its walls, which were built in the 13th century and are still standing today. The city is also home to many historic sites, including York Minster, one of the largest Gothic cathedrals in Northern Europe.