St Mary's Cathedral stands at the western edge of Killarney town, a large Gothic Revival Catholic cathedral in pale limestone. It was designed by Augustus Welby Pugin in the early 1840s and is considered one of the finest examples of Gothic Revival ecclesiastical architecture in Ireland. The soaring nave, the vaulted ceiling, and the elaborate stained glass windows are all worth seeing.
Entry is free and the cathedral is open most of the day. The grounds include a war memorial and a pleasant garden with views of the surrounding hills. The cathedral is about a 15-minute walk from the main bus and train stations and is easily combined with a walk through the town centre.