BUILDERS laying the foundations for Gloucester Green's underground car park discovered the ruins of the old Oxford city prison.

Contractors were carrying out the excavations for the development in July 1987 when they unearthed the fascinating find.

The prison was in use from 1789 to 1878 and was built to replace the medieval Bocardo gaol, which was demolished in 1781.

It consisted of an octagonal central building with two wings, surrounded by a 20ft high curtain wall, and had room for 32 inmates, but records show it was rarely full.

Archaeologists had known the old prison existed but not its exact whereabouts.

The Gloucester Green project was the biggest earth-moving exercise in Oxford for 15 years.