The London Stone

The square mile roughly defines where Roman London stood, and there was a basilica and forum in Cornhill, dating from 70/90AD. Distances were perhaps measured in Roman London from the London Stone (if it were indeed London's "golden milestone"), which was placed in the walled city area. It sits today in a niche in a wall of a bank in Cannon Street.

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A walk around the pavements in the City of London¹ will pass many sights which hint at its ancient history. This area, once a busy place to live, is now the financial centre. As a result it is mostly deserted at the weekend, which makes this a good time for exploration. The Tower of London, St Paul's Cathedral and the Monument are well known to tourists. Even so, a visitor could pass by one of London's oldest, but today perhaps least recognised, landmarks without knowing it.
It is possibly more than 3000 years old, or maybe Druid in origin, but is more commonly believed to be Roman. Located along what some believe to be a ley line connecting significant places, it might well be the mystical centre point of London or even Britain. Once so well recognised that the area and the church were named after it, considered to be the guardian of the City, a place for worship or legal proclamations, a point where all distances from London were measured, mentioned by Shakespeare and Dickens, moved slightly from its original location but currently partially hidden behind an iron grille in the wall of the offices for the Oversea-Chinese Banking Corporation in Cannon Street. Ascribed either mystical, religious, legal or civic significance, it is the London Stone².
Where to Find the London Stone
Come out of Cannon Street Station, cross the road, turn right and walk eastwards a little. If walking it is about 10 minutes from St Paul's Cathedral and the 'Ray of Light' Millennium footbridge³, which leads to the Tate Modern. The Bank is number 111, two buildings away from the London Stone Pub and next to St Swithins Lane (where the road dip indicates the route of the old Walbrook river).
The Stone is set low down into the wall and protected by glass and an iron grille, which is lighted up and reveals a small, blackened, damaged and seemingly insignificant piece of a type of limestone called oolite. This is known to be only a fragment of the original Stone. Most of it is black with city grime although some exposed clean sections indicate damage to the original surface. There are no markings on the Stone but there are two grooves on the top. from here