Shining face of St Paul's

It is London's finest architectural jewel - but for far too long it has been tarnished by the capital's inescapable grime.

Now St Paul's Cathedral is beginning to rid itself of centuries of dirt and dust, to be revealed in all the glory Sir Christopher Wren planned for his best-known masterpiece.

The remarkable results of 13 months of careful scrubbing and scouring of the building's East End are unveiled today after scaffolding was removed.

The work - paid for with £500,000 from an anonymous donor - is the first part of a £ 40 million programme to restore St Paul's for its 300th anniversary in 2008.

The clean-up suggests that once work is complete the cathedral will roundly shame its 20th and 21st-century neighbours.

Layer upon layer of filth has been stripped from the creamy white Portland stone chosen by Sir Christopher in 1675. Four masons and a mason's labourer used fine air-abrasives to protect the stonework. They replaced damaged stones and corroded iron cramps, installed new lightning protection and repointed to protect from rain.

However, perfection was not the aim: scars left by shrapnel during the Blitz were left to tell the cathedral's wartime story. The Dean of St Paul's, the Very Reverend Dr John Moses, said: "Everyone is delighted with the work carried out by our own masons. The generosity of the donor and the skill of the masons have enabled us to see more clearly the warmth of the stone, the delicacy and strength of the carving."

Since the project began in 2000 most of the interior has been cleaned and restored, and the exterior's West Front is due for completion early next year.

Work has started on the South Quire and scaffolding is going up on the South Side, which should be finished by 2007. The final stage is the North Elevation, although £13million must be raised to complete it.

Richard Halsey, at English Heritage, said: "St Paul's have taken a brave decision to clean and repair the entire exterior, but the first phase demonstrates the craftsmanship of their team."