A lump of Lincolnshire limestone - or a clue to the origins of London?

The London Stone, an ancient chunk of masonry referred to by Shakespeare and William Blake that may provide evidence about the capital's origins, is finally to be given a proper showcase, having languished for decades in grubby anonymity.

The stone sits in a glass display case behind a crude iron grill set into the wall of the Singapore-based Oversea-Chinese Banking Corporation building on Cannon Street. But the site is to be redeveloped by the Merchant Property Group, whose new eight-storey development should get the go-ahead from the Corporation of London tomorrow.

The new building will be a vast improvement on the lumpen 1960s office block designed by Biscoe & Stanton in which the stone has been embedded since the demolition of St Swithin's Church, its home from 1742. The relic will now be encased in one of the new building's pillars.

But even its new home hardly does justice to one of London's most potent symbols, referred to by Shakespeare in Henry VI, part II, and Sir Christopher Wren and commemorated in the name of London's first mayor in the 12th century, Henry Fitz-Ailwin de Londonestone.

The stone is thought originally to have been a monolith, or menhir, at the centre of the city. Some authorities claim that it pre-dates the Roman conquest, while others claim it was a Roman milestone, such as existed in the Roman Forum. Blake believed it was used for druidic sacrifices. Many sources believe that for centuries the London Stone was from where proclamations were made.

Some historians, for example Adrian Gilbert, believe the forgotten lump of Lincolnshire limestone is a sign that the city began as a settlement called Trinovantum, founded by Brutus and Trojan refugees two generations after the fall of Troy, and that the "Trinovantes" encountered by Julius Caesar in 54BC were their descendants.

If that were true – and Wren suggested that it was too big to be of Roman origin – the London Stone would be an important artefact. But Mr Gilbert faces a huge challenge to prove his theory because the earliest reference to the stone is in a gospel book written by Ethelstone in the 10th century.