The area around Smithfield, now home to the UK's biggest wholesale meat market, was once one of London's main execution sites. The Elms, as it was called, witnessed the execution of William Wallace (aka Braveheart), as well as hundreds of heretics, who in the medieval era were condemned to death for not following Christianity.
Legend goes that when construction workers dug into the ground in front of St Barts Hospital they cut through a layer of ash - the ashes of those who were burned at the stake for heresy.
Next time you're wandering around there, know that you're walking on the remains of people Queen "Bloody" Mary ruthlessly killed for their beliefs (or lack of) in the 16th century.