York's very own Roman Emperor, Constantine the Great, received some treats on the festival whose date he helped decide.

The Yorkshire Museum's latest exhibition celebrates the man who brought Christianity to the Roman Empire, and helped decide when it should be celebrated.

It all began in York, when in 306AD he was proclaimed Emperor by his troops following the death of his father, Emperor Constantius.

In 325AD, the Emperor called a church council at Nicaea, in modern day Turkey, to determine a standard date for Easter.

More than 300 bishops from all corners of the Roman Empire attended, and after two months of deliberation, they finally issued the Easter Rule.

This stated that all Christians should celebrate Easter on the same Sunday and that this should be the first Sunday after the first full moon following the spring equinox.

The museum's exhibition brings together more than 270 beautiful and fascinating objects and works of art from museums and private collections across the UK and Europe.

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

Gillian Cruddas, chief executive of York Tourism Bureau, said: "This exhibition is set to be one of the highlights of York's tourism calendar this year.

"We will be supporting the celebrations of the 1,700th anniversary of the proclamation of Constantine the Great.

"York's Roman history is always fascinating to many of our four million yearly visitors. We hope, as a city, we can bring the era of Eboracum and Constantine to life."

Updated: 08:57 Monday, April 17, 2006