St Marylebone School is a multi-faith secondary school for girls in the Marylebone area of London. It was founded in 1791 and in 2007 underwent an expansion project, improving space and facilities for the 900 plus pupils it teaches.
Inner London space is at a premium, so the school had the fantastic idea of going down, creating a new gymnasium, amongst other facilities, beneath the existing concrete playground. As they began to look into the practicalities of the project, they received a nasty shock.
The playground formed a coffin lid to over 5,000 corpses, a hangover from the days when the site of the school was the famously overcrowded graveyard of St Marylebone Church. Not to be deterred, the school sought assistance from the Museum of London who excavated the site and eventually ok'ed the project to proceed.
Among the dead they removed from the site were thought to be religious reformer Charles Wesley, painter George Stubbs and architect James Gibbs, most famous for St Martin-in-the-Fields.
For more on what lies beneath London, see our blog Where to find a plague pit.