One of the largest and best-preserved Roman villas yet discovered in Britain has been unearthed by archaeologists.

Built 1,800 years ago on the Isle of Wight, the building is as vast as an Olympic swimming pool and shaped like a church.

“It would have sung out the status of the owner,” Sir Barry Cunliffe, Emeritus Professor of European Archaeology at Oxford University and head of the excavation, told The Times yesterday. “It's a very impressive building, absolutely magnificent. It could have been seen for miles around.”

The discovery comes five years after readers of The Times helped to save spectacular mosaics from another Roman villa found on the same site in Brading, having them removed from the World Monuments Fund's list of endangered sites.

Times Archive, 1923: The Royal visit to Hadrian's Villa

Their Majesties set out early this morning by motor-car for Tivoli

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The remains of yet another important building, constructed up to 150 years before the known villa, were found only days into a five-year exploration of the four-acre (1.6hectare) site. Measuring 50ft (15m) wide and 150ft long, the villa is similar in layout to a church with a central nave and two side aisles. Massive pairs of timbers supporting the roof would have soared up to 20ft in height.

Sir Barry likened it to a medieval hall with the lord of the manor living at one end and a communal space for the estate's inhabitants at the other.

The residential part had under-floor heating and walls plastered and painted with mock marble patterns. The communal end would have been used for meetings and legal matters such as boundary disputes and payment of dues. Although the Victorians explored this part of the site in the 1880s, they dismissed the remains as a barn. Sir Barry said: “They didn't understand what they were excavating. But this was the main building for at least 150 years before the other villa was put up.”

It is comparable in scale to the Bignor Roman Villa, near Pulborough, and the hall of Fishbourne Roman Palace, near Chichester, both West Sussex. Its remains, discovered about 3ft below ground, are so well preserved that the standing structure, its masonry and many roof tiles have survived.

The symmetry and precision of the construction reveals the extraordinary skill of its builder. The tops of the pier bases are all level to within half an inch. Such is the excitement about this excavation that 30 archaeologists from America and Europe are involved.

The later Brading villa's remains had disappeared from sight until 1879, when a couple of local men stumbled across them by chance. Its exceptional mosaics are unrivalled in Britain.

There are depictions of peacocks signifying eternal life, Orpheus charming the beasts of the forest and Tritons, or sea deities, carrying reclining nymphs on their backs. It may have belonged to Allectus, who in AD293 murdered his predecessor Carausius, a Roman army commander who had proclaimed himself Emperor of Britain.

In 2003 Times readers responded to warnings that the mosaics would have to be reburied and removed from public view unless money could be raised to rehouse them. After reading that a protective corrugated-iron structure had been condemned following a flood, they contributed more than £100,000, facilitating the construction of a £3.1million award-winning building. It opened in 2005.

The new site, however, will now have to be covered up. “The remains can't be left open, as they would disintegrate in two winters,” Sir Barry said.

Kenneth Hicks, a trustee of the charitable trust that owns the villa and needs to raise £250,000 to continue the excavation, said: “There are now two villas for the price of one.”

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