St Albans Abbey was a Benedictine abbey at St Albans, Hertfordshire, England. It was founded, according to the sources, in 793 by King Offa of Mercia and dissolved in 1539 during the Dissolution of the Monasteries. The abbey was built around the shrine of Saint Alban, the first British martyr, who was executed in the 3rd or 4th century AD during the Roman period.

The only surviving buildings are the Abbey Gateway (1365) (see photograph, right), which was later used as a prison and is now part of St Albans School, and the Abbey Church (1077), which (since 1877) is now the Cathedral and Abbey Church of St Alban. The other monastic buildings were located to the south of the gateway and church.