Verulamium was a town in Roman Britain. It was sited southwest of the modern city of St Albans in Hertfordshire, England. A large portion of the Roman city remains unexcavated, being now park and agricultural land, although due to ploughing on the privately owned agricultural half of the city a lot of damage has been done, as proven by parts of mosaic floors that have been found on the surface, and results of ground penetrating radar show outlines of buildings as smudges rather than clearly defined walls like those protected by the parkland. Part of the Roman city has been built upon, such as St Michael's church and other parts along the centre of the medieval village. The major ancient Roman route Watling Street passed through the city. Much of the site and its environs is now a scheduled monument.

Roman Britain was the territory that became the Roman province of Britannia after the Roman conquest of Britain, consisting of a large part of the island of Great Britain. The occupation lasted from AD 43 to AD 410.