Carlisle is a city in Cumbria, England. A settlement was first formed here before the birth of Christ, the name being derived from the Celtic word 'Caer', meaning fort. The Romans established a military base here in the 1st century called 'Luguvalium', and there followed a period of prosperity and luxurious living until the 9th century, when the town was devastated by invading Danes. Carlisle Castle was originally a Norman castle made of wood, but was rebuilt using stone taken from Hadrian's Wall. Carlisle Cathedral was founded in 1122 as a Norman Priory for Augustinian canons. The Citadel was built in 1541 during the troubles between Scotland and England as an additional fortification and marks the gateway to the city.