London Stone is a historic landmark at 111 Cannon Street in the City of London. It is an irregular block of oolitic limestone measuring 53 x 43 x 30 cm (21 x 17 x 12 inches), the remnant of a once much larger object that had stood for many centuries on the south side of the street. The name "London Stone" was first recorded in about 1100. The date and the original function of the Stone are unknown, although it is possibly of Roman origin, and there has been speculation about it since at least the 16th century. Modern claims that it was formerly an object of veneration or has occult significance are unsubstantiated.
The present London Stone is only the upper portion of a once much larger object, as described below under History. The surviving portion is a block of oolitic limestone approximately 53 cm wide, 43 cm high, and 30 cm front to back (21 x 17 x 12 inches). Study in the 1960s indicated that the stone is Clipsham Limestone, a good-quality stone from Rutland transported to London for building purposes in both the Roman and medieval periods. More recently Kevin Hayward has suggested that it may be Bath stone, the stone most used for monuments and sculpture in early Roman London and in Saxon times.
Since 1962 London Stone has been located on the north side of Cannon Street, opposite Cannon Street Station, housed in an aperture in the wall of number 111 Cannon Street (London EC4N 5AR), surrounded by a decorative Portland stone fascia with an iron grille. Inside the building it is protected by a glass case. The stone and its surround, with the iron grille, were designated a Grade II* listed structure on 5 June 1972.