From Travel Info
Londonderry is also known as Derry and the city itself if an ancient city, rich in culture and architecture reflective in the three names attributed to the city.
Derry derives from Gaelic, Doire, which is reminds us of the oak grove upon which Saint Columba established a monastry in about 546 AD.
Londonderry is name placed upon the city in the 17th Century during the Plantation of Ulster.
Then the The Walled City is reflective of Londonderry's status as one of the best maintained walled cities found in Europe.