Large properties just inside city walls, identified using radar, would have been equivalent to homes worth millions today

Foundations of three large Roman houses preserved for almost 2,000 years have been discovered in a park in the centre of Chichester.

James Kenny, an archaeologist at Chichester district council, believes that when fully excavated they will prove to be some of the best Roman houses found in a city centre in Britain.

“To find what appear to be well-preserved Roman remains in one of the few stretches of open ground in a city which has been continuously built and rebuilt ever since the days of Alfred the Great is really exciting,” Kenny said. “Particularly since this city had no mains drains until so late – not until the 1880s – it is absolutely pockmarked with centuries of cesspits and rubbish dumps, so very little undisturbed Roman material remains.”

The foundations were identified through ground-penetrating radar tests in Priory Park, just inside the north-east corner of the Roman walls. A small test dig has confirmed extensive masonry foundations, as well as some tesserae from mosaic floors.

“We dug our test pit just down to the floor surface, which was very level and smooth, and extremely well made – it’s certainly not unrealistic to think it was made to take a mosaic,” Kenny said.

The houses, built around central courtyards, would have been for the wealthy, on the edge of the city away from the noise and smells of the central market and workshops. One has an unusual rounded end, which could indicate part of a bath house.

Kenny hopes to raise money through a Heritage Lottery Fund bid for a community archaeology project, with local amateur archaeologists and members of the public joining in the work.

“The location marks what may have been one of the more affluent parts of the Roman town, with these houses being the equivalent to a property worth millions of pounds in today’s society,” he said. “The two houses have walls surrounding complete rooms, which are set around a courtyard or atrium. There is also a deep masonry building with a rounded end. We are intrigued to find out what this building is. It could be a cellar, part of a bath house, or something even more exciting.”

He believes the houses were originally set on a Roman street, which was largely destroyed when a reservoir was built in the park in the second world war as an emergency water supply.

“It seems logical to think they must have hit some of the Roman masonry, but there is absolutely no record of it if they did. I’m looking at a photograph now of four blokes in overalls with spades, obviously digging it out by hand – there’s no sign of a tweedy archaeologist type standing around watching them.”

The park also holds the 13th-century guildhall – originally the chancel of a Franciscan friary – and the mound of a Norman castle: the builders of both probably used above-ground Roman remains as a handy source of cut stone.

The houses were identified through tests by David Stavely, a computer programmer by day and expert on geophysics, with a particular interest in Roman roads, who took holidays from work to carry out the survey.

He originally intended to scan Chichester’s pavements in search of the network of buried Roman roads, but Kenny suggested that because of the below-ground disturbance among the modern streets, he might try Priory Park instead.

The park was given to the city as a first world war memorial by the Duke of Richmond.

Chichester, known in Roman times as Noviomagus Reginorum, which developed from a military fort into a thriving town, still has remains of its Roman walls, although the visible masonry is mostly medieval and later restoration.

Roman fragments and a few complete building sites have been discovered in the city centre, including carved columns and handsome mosaics – one is displayed through a glass panel under the cathedral – and a 2nd-century AD bath house found in the 1970s, now displayed in the Novium museum.