A British settlement existed nearby. During the Roman occupation, as Verulamium ,it became one of the most important centres in Britain; at the junction of two of the great Roman roads, it was the only centre in Britain whose inhabitants were Roman citizens. It was destroyed by Boudicca but soon rebuilt. A small part of the Roman wall still can be seen at a popular lakeside picnic spot.
It all but disappeared after the Romans left. In 793 Offa founded a Benedictine abbey there, which, with its importance as the place of St. Alban’s martyrdom, was given precedence and by the late 11th century, its nave was the second longest in Europe.
Two of the battles of the Wars of the Roses were fought nearby: the first (1455) - hardly more than a skirmish - launched the conflict; and saw a victory to the Yorkists. The second, in 1461, was a Lancastrian victory. In the English Civil War St. Albans was the headquarters of the Parliamentary army.
Today, St. Albans is commuter territory - part of the greater London dormitory belt for those who can’t quite afford to live in the outskirts of London itself.
Reference: “Brewer’s Britain and Ireland”