Some time in 2005 visitors will be able to visit the tall narrow Georgian house in the heart of London where Benjamin Franklin once sat stark naked by the large first floor sash windows, "air bathing" and thinking about bifocals, electricity, economics, American politics, British diplomacy, or how to get the fire in his back room to draw better.

It is a fair bet that however passionately interested the visitors are in the political history of American independence, and the intellectual history of the Age of Enlightenment, what will transfix them is the windowless basement room, once part of the garden.

As restoration work by the Friends of Benjamin Franklin House began on 36 Craven Street, a Grade I listed house rescued from the brink of tottering collapse, a small pit was found in the basement room. A human thigh bone was found.

The coroner and the police were notified. Excavation continued. More human bone surfaced. And more. And more, until more than 1,200 pieces of bone were recovered.

Since the bones were too ancient to trouble Scotland Yard, they are now in the care of the Institute of Archaeology, where experts have already determined that they range from an old man to a human baby. Several skulls have been trepanned, and arm and leg bones chopped through.

The most plausible explanation is not mass murder, but an anatomy school run by Benjamin Franklin's young friend and protege, William Hewson. He had been a pupil of the most brilliant anatomist of the day, William Hunter, but the two fell out and Hewson started his own anatomy school - at the home of his mother-in-law Margaret Stephenson, just off the Strand, where Benjamin Franklin was also a lodger for 16 years.

He had a rich source of subjects at hand: the resurrection men could deliver bodies stolen from graveyards to the Thames wharf at the bottom of the street, while there was a weekly public execution at the gallows on the other side of the garden wall.

Benjamin Franklin, who was interested in absolutely everything - he was lucky to escape killing himself or his guests at the demonstrations of electricity he was wont to give during dinner parties - must have attended the public dissections.

Hewson died young of blood poisoning after he cut himself during a dissection.

Franklin eventually returned to the United States, but was estranged from his abandoned family, and separated from the illegitimate son who shared his London years when Franklin declared for American independence and the son was exiled for his loyalty to England.

The house was less than 30 years old when Franklin came to London and rented the best first floor rooms, where he was visited by all the leading figures in radical politics, science and philosophy.

It continued as a boarding house, became a small hotel and then offices, but gradually became derelict.

It was always a shrine to visiting Americans, as the only surviving home of Benjamin Franklin on either side of the Atlantic, but by the 1970s when it was given to the Friends of the Benjamin Franklin House it was near collapse.

It has taken until now to find the money to restore the house, and they are still raising the last £900,000.

The house has survived flooding, fire, rot, and the second world war bomb which demolished the two houses opposite it in the narrow street, with most of its original features battered but intact, including handsome panelling, window shutters and staircase - and the frame for the metal damper which Franklin designed, and did install in the troublesome back room fireplace.

· www.thersa.org/franklin

Founding father and inventor

· Benjamin Franklin was born in Boston in 1706, the son of a chandler and the 15th of 17 children

· First apprenticed at 12 as a printer to his brother James, he established a successful printing house, founding Poor Richard's Almanac, celebrated for its aphorisms

· He was elected to the colonial assembly, but his invention of the Franklin stove led him to turn to researching electricity in 1746

· His work established the distinction between positive and negative electricity, and showed that lightning and electricity are the same. He was among the first to advocate lightning conductors

· He is credited with discovering the path of storms across North America, the direction of the Gulf Stream and the properties of colours in absorbing light

· In 1764 he was sent to England to dispute the right of parliament to tax America without representation. In 1775 he was a founding father who helped draft the Declaration of Independence

· In signing the declaration he warned colleagues: "We must indeed all hang together, or most assuredly we shall surely all hang separately."

· He negotiated the French arms and money which enabled the colonists to win the war of independence. Franklin also negotiated the treaty which ended it

· He retired from public life in 1788 but in 1790, the year of his death, invented bifocal spectacles

· John Ezard