Elias Shama's small souvenir shop in Nazareth, the town of Jesus's childhood, barely catches the eye. Tourists usually pass by it on their way to the neighbouring Mary's Well church, claimed by the Greek Orthodox church as the site where the Archangel Gabriel revealed to Mary that she was carrying the son of God.

Before the Palestinian intifada erupted three years ago, the shop did a steady trade selling the usual pilgrim fare - olive-wood crosses and Virgin Mary statuettes - to any tourist who strayed from the 100 or more coach parties briefly herded into the city each day from across Israel. Now, with constant stories of Palestinian suicide attacks in the news, the pilgrims are long gone.

This summer, though, Shama's shop, Cactus, attracted a handful of visitors prepared to brave the violence. A team of forensic archaeologists and biblical scholars have been poring over a network of tunnels Shama unearthed under his shop several years ago. They believe he has made a discovery so remarkable it will rewrite the history books, changing our understanding not only of the Holy Land but of the life of Jesus himself.

Shama began excavating the tunnels after he and his Belgian wife, Martina, bought the shop in 1993, and found a series of 4ft-high passages, separated by columns of small bricks supporting a white marble floor. In one corner they found a walled-off room where a residue of wood ash revealed it once served as a furnace.

The American excavators are convinced that what Shama has exposed is an almost perfectly preserved Roman bathhouse from 2,000 years ago - the time of Christ, and in the town where he was raised. In a piece of marketing that is soon likely to be echoing around the world, Shama says he has stumbled across the "bathhouse of Jesus". The effects on Holy Land tourism are likely be profound, with Nazareth becoming a challenger to Jerusalem and Bethlehem as the world's most popular site of Christian pilgrimage...