HE was the most influential man York has ever known and his path to glory - which began 1,700 years ago - put the historic city on the Roman map.

Today, the great Roman emperor Constantine was once again in royal company as the city he adopted in 306AD paid tribute to him.

The Princess Royal, Princess Anne was visiting York to open a major exhibition celebrating his reign over the Roman Empire, the repercussions of which are still felt to this day.

The exhibition, at the Yorkshire Museum, in association with the British Museum, brings the era of Constantine The Great to life with more than 270 fascinating objects and works of art from 36 different museums across the UK and Europe.

Highlights include a magnificent marble sculpture of Constantine's head, found in York and believed to be the earliest portrait of him.

Also featured is the Hinton St Mary mosaic, discovered in Dorset, which contains the only head of Christ pictured on a mosaic in the Roman Empire, and is rarely seen outside its home at the British Museum.

Janet Barnes, exhibition organiser, said: "Constantine is accepted as one of the great emperors of the Roman Empire whose ability and vision reshaped the world in which we live.

"His destiny meant that his story began here in York, and his extraordinary achievements give us a worthy subject to celebrate."

Constantine inherited the right to succession from his father in 306AD and established himself as a true leader in his own right after a conclusive victory at the Battle of Milvian Bridge in 312.

This was one of many successful campaigns, but it is perhaps the most notable as Constantine experienced divine intervention on the eve of battle.

He embraced Christianity, then a religion practised by a persecuted minority, and accorded everyone the religious freedom to worship whichever gods they chose.

Constantine was responsible for changing the course of history. He reunified the Roman Empire, founded a new capital city at Constantinople, and embraced a new religion.

Dr Christopher Kelly, a leading expert on the Roman Empire based at Cambridge University, said: "There is no doubt that without Constantine's active support and commitment, Christianity would not have become the majority religion of the Roman Empire. Without Constantine, the history of Europe would have been strikingly different."

The Princess Royal will also be attending the Pageant of the Donkey at York Minster, organised by the Guild of Freemen and Riding For The Disabled.

The service consists of a series of pageants which are a reminder of the part played by the donkey in the life of Christ.

Updated: 09:34 Thursday, March 30, 2006