LONDON - It was built as the most northerly limit of the mighty Roman Empire, and remains the largest Roman artefact anywhere in the world. Later this year Britain's Hadrian's Wall will spring to life when the Romans return for what will be the biggest event of its kind ever staged.

Like the larger Great Wall of China, Hadrian's Wall was built as a frontier fortification to stop invasions.

It was built on the orders of Roman Emperor Hadrian who ruled the empire from the year 117, making this year the 1,900 anniversary of his 21-year reign.

This year also marks the 30th year since UNESCO declared Hadrian's Wall a World Heritage Site.

From April 8 until September 10, a program of events is to take place along the 118 kilometer wall, centered on Hadrian's Cavalry who guarded the border.

Events include spectacular re-enactment events, a cavalry exhibition and a specially commissioned piece of contemporary art.

The new exhibition will also feature one of the largest Roman Cavalry re-enactments ever seen in Britain. It has brought together 10 museums and visitor attractions all telling stories of Hadrian's Wall.

Taking place in border city Carlisle, the re-enactment will showcase some of the exercises the cavalry would have performed on training grounds at sites across the wall, as described by Emperor Hadrian himself almost 2,000 years ago.

It will, say the event organisers, be an amazing spectacle and unique to this exhibition.

The exhibition will bring together a unique group of Roman cavalry objects including ornate helmets, armour and weapons on loan from national and international museums, which will be shown alongside objects from museums across the wall.

National and international museums involved in the six-month festival include the British Museum, National Museums Scotland, the Musee d'Art Classique de Mougins (France), Archaologisches Landesmuseum Baden-Wurttemberg/Limes Museum, Aalen, the Archaeological State Collection, Munich, and the Landesmuseum Württemberg, Stuttgart (Germany).

The events take place along the much longer Hadrian's Wall World Heritage site which spans 150 miles, straddling the current borders of England and Scotland between the North Sea and the Irish Sea.

Bill Griffiths, chair of the event organisers, the Hadrian's Cavalry steering group, said: "This is a once in a lifetime experience, bringing together for the first time these very special Roman cavalry objects."

The cavalrymen were famous for their lavishly decorated helmets and body armour. The cavalry horses were also held in high esteem; enjoying customised stabling in barrack blocks built to accommodate the riders and their mounts, he said.

"Hadrian's Cavalry will reveal the story of the Roman riders through a unique exhibition spread across 10 museums and heritage attractions, each with its own special exhibition and objects.

"Never before have people been able to see this collection of Roman cavalry objects in the actual locations they would have been used," Griffiths said.

Jane Tarr from Arts Council England said: "Visitors to the world heritage site and local audiences will get to see world class objects, many in the locations they would have been seen 2000 years ago."

Along the entire length of the wall there was a fort every five Roman miles, about every 1.5 kilometers. Roman guards were also posted at mileposts, each around 1,000 foot paces apart.

It took three legions of Roman soldiers between 10,000 and 15,000 men, six years to complete the wall.

The Romans ruled what was known as Britannia following an invasion by Julius Caesar around 55 AD, finally ending their rule after almost 400 years.