A PREVIOUSLY unknown church, which is believed to be at least 1000 years old, has been unearthed beneath Lincoln Castle.

Archaeologists have described it as a significant find that will greatly add to knowledge of early Christianity in the area. The unexpected location, under the castle, however, has posed a puzzle.

The church, which is Anglo-Saxon, and believed to date from about the tenth century, was exposed during excavations for a lift shaft, more than nine feet below today's ground-level.

Experts have always thought that the city's first cathedral, also built in the tenth century, lies near by, under the present cathedral, which dates from the Norman Conquest. Experts say that the new discovery shows signs of being an important high-status church - possibly a Saxon minster, or part of an adjacent monastery or palace.

Lincolnshire County Council's historic-environment manager, Beryl Lott, said: "This is a very exciting discovery. Our knowledge of the site between the end of Roman period, and when the castle was built, is very scant. While the discovery was totally unexpected, it is well known that other Roman walled towns often contained some form of high-status use during the Anglo-Saxon period."

The earliest church in Lincoln was St Paul in the Bail, which was probably built in the seventh century on the site of the Roman forum. It was destroyed and rebuilt on several occasions, and its Victorian successor was finally demolished in 1971.

The work for the lift shaft exposed a limestone coffin with a lid still mortared in place, and archaeologists hope to insert an endoscopic camera into the coffin to see what is inside.

Dr Martin Carver, Emeritus Professor of Archaeology at the University of York, said: "This is a wonderful find. The most important thing is to get a close look inside.

"The Romans used stone sarcophagi, including Christian ones in the fourth century AD, and the early Christian English re-used them in the seventh. But Late Saxon stone coffins are pretty rare. If it has an occupant, we can bring the toolbox of modern forensic archaeology to bear, and find out more about them: place of birth, diet, health, wounds, date of death, and more."

In the wall opposite, the dig uncovered human bones laid in a niche in the foundation. They were originally wrapped in a finely woven textile - tiny impressions of the cloth can be seen on the mortar of the wall. The burial is thought to be a "votive deposit", and may be the relics of a holy person placed inside the wall to dedicate the building. Radiocarbon dating will be used to find their exact date.

The work is part of a £20-million project to restore and promote the heart of the city in and around Lincoln Cathedral.