Built between 1628 and 1633 from the same grey-green schist as the city walls, this was the first post-Reformation church to be erected in Britain and Ireland, and is Derry's oldest surviving building.

　　In the porch (under the spire, by the St Columb's Court entrance) you can see the original foundation stone of 1633 that records the cathedral's completion. The smaller stone inset comes from the original church built here in 1164.

　　Also in the porch is a hollow mortar shell fired into the churchyard during the Great Siege of 1688–89; inside the shell were the terms of surrender. The neighbouring chapter house contains more historical artefacts, including paintings, old photos and the four huge padlocks used to secure the city gates in the 17th century.