Archaeologists in London have started excavating some 3,000 skeletons at the historic Bedlam burial ground which was used between 1569 and 1738 and was named after the Bethlem Royal Hospital or “Bedlam,” one of the world’s oldest psychiatric institutions.

The site was found during the excavations for London’s new Crossrail line, at the entrance of the city’s new Liverpool Street station.

Approximately 20,000 Londoners are believed to have been buried in the specific location, including victims of the English Civil War, the Great Plague and the Great Fire of London.

A team of 60 researchers will work six days a week over the next month to recover the skeletons, which will be re-buried at a different cemetery in London.