A major new exhibition, officially opened in York today by the Princess Royal, celebrates the city's links with the man credited with the acceptance of Christianity as a mainstream religion and the subsequent effects on the religious and political make-up of the West.
Constantine was in York in 306AD on a military campaign led by his father, the co-emperor Constantius, and on his death the fortress's legions proclaimed his son emperor.
Six years later, before leading his troops to victory in the battle of Milvian Bridge, outside Rome, Constantine saw a vision of the Christian symbol of the Chi-Rho.
The emperor was converted to the faith and promoted religious tolerance, ending the persecution of Christians and initiating the building of the first Christian church in Rome and St Peter's Basilica. He also presided over the drafting of the Nicene Creed, which is still used by Christians today.
Constantine the Great: York's Roman Emperor, at the Yorkshire Museum in York, for the first time brings together artefacts from dozens of museums across Britain and Europe to illustrate the power and prosperity of the Roman empire in the time of Constantine.
Some of the treasures on show did not have far to travel – a marble sculpture of the emperor's head, a key image of the event, was unearthed during archaeological excavations in Stonegate in the city centre and is in the care of York Museums Trust.
The trust is running
the exhibition, which is curated by Elizabeth Hartley and designed by Ivor Heal.
A year of celebrations will include a special service at York Minster on July 25, the 1,700th anniversary of the proclamation of Constantine as emperor.
The same month, York University hosts an international academic conference.
Constantine the Great: York's Roman Emperor runs until October 29.