The Order of St John’s first hospital was recently unearthed during work on a site in Jerusalem that is being transformed into a restaurant.

The 900-year-old building is the first place where the Hospitallers used an ambulatory service to bring in the sick and wounded on camels and horses.

It is the largest of its era to be discovered in the Middle East region, standing six metres high in the heart of the Christian quarter in the Old City of Jerusalem.

The Israel Antiques Authority said the building where the excavations were taking place served as a fruit and vegetable market until a decade ago. The archaeological project was prompted by a planning permission request by the Grand Bazaar Company of East Jerusalem to turn the place into a restaurant.

According to building project manager Monser Shwieki, the developers want to incorporate the historic building into the planned restaurant and the site will be open to the public next year.

The structure is characterised by massive pillars and ribbed vaults. The antiques authority said the place was a great hall composed of pillars, rooms and smaller halls.

The Order of Malta traces its history to an 11th century infirmary in Jerusalem set up by a monk to care for pilgrims and was officially recognised by Pope Paschal II 900 years ago.

“We’ve learned about the hospital from contemporary historical documents, most of which are written in Latin. These mention a sophisticated hospital that is as large and as organised as a modern one.

“The hospital was established and constructed by a Christian military order named the Order of St John of the Hospital in Jerusalem.

“These righteous warriors took an oath to care for and watch over pilgrims and, when necessary, they joined the ranks of the fighters as an elite unit,” a spokesman for the authority said.

The hospital could accept 2,000 patients of different religions and functioned as an orphanage for abandoned newborns as well.

Once known as the Hospitallers, the Knights of Malta are now providing aid in war zones and countries hit by natural disasters.