The Heart of Midlothian is a mosaic located outside St Giles' Cathedral in Edinburgh. The heart marks the location of the entrance to Edinburgh's Old Tolbooth which was demolished in 1817. Locals will often spit upon the heart as a sign of good luck. While the tradition is now one of good luck, it was originally believed to be done as a sign of disdain for the executions which took place within the Old Tolbooth.
The Edinburgh football team Heart of Midlothian F.C. takes its name from the Old Tolbooth, and the mosaic which marks its former location.
Wikipedia https://en.wikipedia.org/wiki/Heart_of_Midlothian_(Royal_Mile)
Address 375 High Street, Edinburgh EH1 1QS, United Kingdom
Coordinates 55°56'58.436" N -3°11'29.318" E