Israeli archaeologists displayed yesterday a 2,000-year-old stone block unearthed in Jerusalem that they hope will help shed new light on a Jewish revolt against the Romans.

It is part of a lintel from an arch built to welcome Emperor Hadrian when he visited Jerusalem in 130 AD, around the time the region's Jews, led by Bar Kochba, rose up against Roman rule.

The Latin inscription on the remnant, which hails Hadrian in the name of the 10th Roman legion, fills out understanding of the extent to which the empire controlled Judea at the time, said Israel Antiquities Authority archaeologist Rina Avner.

"This is another (part in the) puzzle in the historical mystery of what preceded what: the revolt of Bar Kochba or the foundation and the establishment of a city on top of the ruins of Jerusalem named 'Aelia Capitolina' and the change of status of Jerusalem to a Roman colony," she said. "We don't know yet which preceded which."

The Israel Antiquities Authority said the find could contribute to answering the long-standing question of why the Bar Kochba revolt erupted - over the establishment of Aelia Capitolina and the construction of a pagan temple on the site of the destroyed Jewish temple, or because of Hadrian's punitive actions against those resisting Roman rule.

The large fragment, weighing several hundred kilograms, was a surprising find. Archaeologists were working to recover Byzantine pottery around a water cistern at a site near Jerusalem's Old City ahead of construction work.

Avner said the Byzantines, who succeeded the Romans, did not preserve their predecessors' monuments and recycled the stone for their own building projects. The newly discovered section has had a semi-circle hewn out of it and was used as a paving stone around a water cistern.

The upper part of the inscription is also mostly erased because it was exposed. The part that was buried has retained clearly the Roman letters that has got researchers excited.

"All the pottery at the site was Byzantine and all we wanted to do was to dismantle an upper course of stone...in order to find pottery and to more or less accurately be able to date the cistern," Avner said.

While around a dozen such welcoming arches for Hadrian have been discovered in the eastern Mediterranean area, the one in Jerusalem is the only one certain to have been erected by Hadrian's own soldiers.

Another part of the lintel was discovered in the 19th century by French archaeologist Charles Clermont-Ganneauand and has long been on display at the Studium Biblicum Franciscanum Museum in the Old City.

Jews rebelled against the Romans twice, but were eventually defeated - first, around the time Herod's Second Temple in Jerusalem was destroyed in 70 AD, and then around 132-135 AD, under legendary leader Bar Kochba.