London Stone was originally situated in the middle of Cannon Street and was much larger than it is now. If it was Roman it might have been part of a Roman office building between the principle Roman Street and the Thames, the remains of which were excavated beneath Cannon Street Station MOL. It is shown on the 1550s copperplate map of London, as a large block of stone in Candlewick Street (now Cannon Street) outside St Swithin's Church. The church was destroyed in the Great Fire of London in 1666, and rebuilt by Christopher Wren, who encased the old stone in a larger protective carved stone. By 1742, the stone had become an obstruction to traffic, and was moved from the south side of Cannon Street to the north side. For similar reasons, it was moved again in 1798, and by 1828 was set into the south wall of St Swithin's Church, on the north side of Cannon Street. In 1941 St Swithun's church was gutted in the Blitz but the stone was left unscathed. In 1962 the Wren church was demolished and replaced by the current building at 111 Cannon Street, where the stone is placed in an alcove in the wall.
The stone and box, with iron grille, were designated a Grade II listed structure on 5 June 1972. A decorative grille to protect the stone had been provided by the London and Middlesex Archaeological Society in 1869; it is clear from old photographs that the present grille is not the original, but a version made in similar style in 1962. There are current proposals to move the stone further down Cannon Street to allow the building into which it is built to be redeveloped.
The nearest London Underground and National Rail station is Cannon Street — the station's main entrance is opposite the Stone on Cannon Street. There is also a pub nearby called "The London Stone".
