The date of the execution is best left to the venerable Bede: "when the cruel Emperors first published their edicts against the Christians". In other words, sometime after the publication of the edicts by Eastern Roman Emperor Diocletian in 303 and before the proclamation of the toleration Edict of Milan by co-ruling Roman Emperors Constantine I and Licinius in 313. The year 304 has been suggested.
In 1968, English historian John Morris suggested that St Alban's martyrdom took place during the persecutions under Emperor Septimus Severus in 209. Morris bases his claims on earlier manuscript sources, unknown to Bede, especially an 8th-century copy of a 3rd century manuscript found in Turin which states, ""Alban received a fugitive cleric and put on his garment and his cloak (habitu et caracalla) that he was wearing and delivered himself up to be killed instead of the priest.... and was delivered immediately to the evil Caesar Severus." St Gildas knew this source, but mistranslated the name "Severus" as an adjective, and wrongly identified the emperor as Diocletian. Bede accepted this identification as fact, and dated St Alban's martyrdom to this later period. As Morris points out, Diocletian reigned only in the East, and would not have been involved in British affairs in 304; Severus, however, was in Britain from 208 to 211. Morris thus dates Alban's death to 209. Subsequent scholars (W.H.C. Frend and Charles Thomas for example) have argued that such a single, localized British martyrdom in 209 would have been unusual, and have suggested the period of 251-259 as more likely.
Alban sheltered a Christian priest (Geoffrey of Monmouth's later interpolation giving his name as "Amphibalus", the name for the cloak) in his home, and was converted and baptised by him. When the "impious prince", as Bede has called him, sent Roman soldiers to Alban's house to look for the priest, Alban exchanged cloaks with the priest and was arrested in his stead at Chantry Island. Alban was taken before the magistrate, who was furious at the deception and ordered that Alban be given the punishment due to the priest if he had indeed become a Christian. Alban declared, "I worship and adore the true and living God who created all things." These words are still used in prayer at St Albans Abbey. St Alban was eventually sacrificed to the Roman gods and was condemned to death. He was taken out of the town across the River Ver to the top of the hill opposite. The reputed place of his beheading is where St Albans Cathedral now stands.
Bede tells several legends associated with the story of Alban's execution. On his way to the execution, Alban had to cross a river, and finding the bridge full of people, he made the waters part and crossed over on dry land. And the executioner was so impressed with Alban's faith that he also converted to Christianity on the spot, and refused to kill him. Another executioner was quickly found (whose eyes dropped out of his head when he did the deed), and the first was killed after Alban, thereby becoming the second British Christian martyr.
Alban is represented in art as carrying his head between his hands, having been beheaded.
The Fellowship of Saint Alban and Saint Sergius is named in part after Alban.
The Washington National Cathedral, an Episcopal Church in Washington DC, USA, is located on Mount St. Alban.
An example is the coat of arms for the Austrian community of Matrei: it depicts St Alban with his head in his right hand and a sword in the left hand, although the local church is dedicated to Albinus.
The largest relic of St Alban in England is the thigh of the protomartyr preserved at St Michael's Benedictine Abbey, Farnborough, Hampshire, which was removed from the St Pantaleon's reliquary in the 1950s.