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, though much has been built upon. The major ancient Roman route Watling Street passed through the city. Much of the site and its environs is now a scheduled monument.
Before the Romans established their settlement, there was already a tribal centre in the area which belonged to the Catuvellauni. This settlement is usually called Verlamion. The etymology is uncertain but the name has been reconstructed as *Uerulāmion, which would have a meaning like "[the tribe or settlement] of the broad hand" (Uerulāmos) in Brittonic. In this pre-Roman form, it was among the first places in Britain recorded by name. The settlement was established by Tasciovanus, who minted coins there.
The Roman settlement was granted the rank of municipium around AD 50, meaning its citizens had what were known as "Latin Rights", a lesser citizenship status than a colonia possessed. It grew to a significant town, and as such received the attentions of Boudica of the Iceni in 61, when Verulamium was sacked and burnt on her orders: a black ash layer has been recorded by archaeologists, thus confirming the Roman written record. The rebuilt town grew steadily; by the early 3rd century, it covered an area of about , behind a deep ditch and wall. It is the location of the martyrdom of the first British martyr saint, Saint Alban, who was a Roman patrician converted by the priest Amphibalus.
Verulamium contained a forum, basilica and a theatre, much of which were damaged during two fires, one in 155 and the other in around 250. One of the few extant Roman inscriptions in Britain is found on the remnants of the forum (see Verulamium Forum inscription). The town was rebuilt in stone rather than timber at least twice over the next 150 years. Occupation by the Romans ended between AD 400 and 450.