Of the two million people who visit Bath each year, 99 per cent are missing out on the city's greatest art treasures.
igh above Bath in a dank graveyard lie three men whose contribution to the artistic life of the city is easily overlooked by culture vultures with time only for the Roman Baths, the Pump Room and Royal Crescent.

Pre-eminent behind tangles of brambles and ivy is the granite tomb of William Beckford, a man whose fortune from sugar plantations in Jamaica was so great that Byron described him in Childe Harold as "England's wealthiest son". Nearby is Henry Edmund Goodridge, the architect who worked for Beckford and designed the 154-ft Italianate tower that dominates the old cemetery. Beckford's dog was supposed to be in this company, but the Church objected and its body was removed.

The third grave is that of Sir William Holburne, the naval officer turned art connoisseur, whose collection forms the nucleus of the Holburne of Menstrie Museum, housed in an elegant Georgian building at the end of Great Pulteney Street. Unfortunately, it is the wrong end for most visitors to Bath. Though they linger by the shops on Robert Adam's Pulteney Bridge over the Avon, too few venture further away from the city centre. Each year, some two million people visit the city but no more than 20,000 visit the Holburne. To the exasperated keeper of the art, Dr Ann Sumner, it is "like going to Glasgow and not visiting the Burrell Collection". Its quality is more frequently compared to the Wallace Collection, with paintings by Gainsborough, Stubbs, Reynolds, Ramsay, Raeburn, Angelica Kauffman and Zoffany.

Holburne and Beckford may have been wealthy, but those who have care for their legacies to Bath are in need of considerable sums of money. The Beckford Tower Trust has embarked upon a pounds 500,000 project to restore the dilapidated Grade I-listed building, but although they have secured lottery funding the Trust must raise pounds 100,000 in matching funding.

The museum and the tower are both getting a promotional hand from Christie's through a "Beauties of Bath" exhibition, which opens at the auction house's galleries in St James's, London, on Wednesday.

One of the highlights from the Holburne is Antonio Susini's bronze figure, Kneeling Woman Bathing, which, although Sir William did not know it, once belonged to Louis XIV. The French royal inventory number, 35, is engraved on the woman's back, beneath her left shoulder. Also making the journey from its pride of place before a window looking directly down Pulteney Street is Joseph Plura's masterpiece, Diana and Endymion, actually made in Bath in 1752.

While the museum's collections, including silver, porcelain, fine furniture and 17th- and 18th-century Dutch and Italian Old Masters, are of national quality, it has strong associations with Georgian Bath. The building was once the Sydney Hotel, the centrepiece of the pleasure gardens frequented by Jane Austen.

Nathaniel Hone's miniature of Beau Nash, Bath's master of ceremonies, is on display at Christie's, as is Angelica Kauffman's 1777 painting of 11-year old Henrietta Laura Pulteney. It is the only surviving image of the daughter of Sir William Pulteney, who collaborated with Robert Adam in the development of Bath and was, like Beckford, labelled by his wealth - "the richest commoner in England" was Pulteney's tag.

Thomas Gainsborough spent 16 years in Bath, during which time he developed his portrait style. On display is the artist's first full-length male portrait set in a landscape portraying Dr Rice Charleton, his friend and doctor. Charleton was a senior physician at the Bath Mineral Water Hospital and the portrait, together with others of his children, was probably painted in lieu of medical bills.

While the Holburne Beauties of Bath exhibition in the auction house's Great Rooms contains the finest works of art, the complementary exhibition in the Book Room, William Beckford and Lansdown Tower, tells the stranger story. Recreating the Tower's interior as it was at the time of Beckford's death in 1844, it features chairs and cabinets that once furnished the sumptuous rooms and oil paintings illustrating the objets de vertu once kept there.

The Tower was Beckford's second extraordinary creation. The first was Fonthill Abbey in Wiltshire, a neo-Gothic monstrosity built by James Wyatt and intended to rival Salisbury Cathedral. Beckford was briefly an MP, but for all his wealth and gifts as a musician, linguist and art collector, he was not a happy spirit. His wife of only three years. Lady Margaret Gordon, died after giving birth to their second daughter. "Some people drink to forget their unhappiness, I do not drink - I build," he said.

To emphasise the vastness of the baronial hall at Fonthill, Beckford had the 35-foot high doors opened and shut by a dwarf he had plucked from poverty in Italy. But by the 1820s, the building of Fonthill and the poor management of his sugar plantations were draining even Beckford's deep coffers. He sold up and moved to Lansdown Crescent in Bath. Three years after his departure, the main tower at Fonthill collapsed. By then, though, he was engaged on another tower. By no means broke, he had bought all the land behind his house to the top of Lansdown Hill. An ornamental route was created, up which Beckford could ride to the tower - a "treasure trove" for the finest works of his collection and a retreat for study.

Lansdown Hill, Beckford told a friend, offered "the finest prospect in Europe". The top of the tower is 870 feet above sea level. The style of the belvedere and lantern is believed to have been inspired by the Temple of the Winds in Athens and the Chogagic Monument in Lysicrates. Inside, it was hung with damask curtains lined with scarlet serge and bordered with silk lace. A small sanctuary contained a marble statue by Rossi of Beckford's favourite saint, Anthony of Padua.

But the story of the tower after Beckford's death is a sorry one. There were plans to turn it into a beer garden, but Beckford's daughter was so appalled, she bought it back and gave it to the church. It became a funerary chapel surrounded by a cemetery. Decades of dilapidation followed. A mysterious fire gutted the building in 1931 and, in 1969, it was described by the Rector of Walcot, desperate to be rid of the liability, as having "neither ancient value nor contemporary interest; it's not even a good folly".

Sold, the Tower was rescued from certain dereliction by Elizabeth and Leslie Hilliard who converted it into a home-cum-museum. The burden was handed on in the early 1990s, and now a dedicated trust has embarked on essential structural repairs.

"The tower is a remarkable monument to the errant genius of its creator," says Sidney Blackmore of the trust. In the long-term, Blackmore would like to return some of the interiors to the plush decorative appearance they had at the time of Beckford's death. And he would like to find the massive granite vase, ornamented with bronze, that stood at the centre of the stairwell. "It's so big, we assume its not far away, probably buried in somebody's garden."

The Beckford Tower Trust has taken on an ambitious project and, like the Holburne, it could find that drawing visitors out from Bath's central attractions is a frustrating business. It would be a shame if they cannot find benefactors through their exposure at Christie's. Three denizens of the Lansdown graveyard could certainly rest easier

"Beauties of Bath" is at Christie's, London, until 3 February