The remains of three near-complete Roman buildings have been discovered under a city centre park, archaeologists have revealed.
Scans using ground-penetrating radar appear to show two large masonry houses and an unusually-shaped third building dating back more than 1,000 years.
Civic leaders in Chichester, West Sussex, have hailed the discovery of the three properties - worth millions of pounds in today's property market - as being of national historical importance.
James Kenny, archaeologist at Chichester District Council, said it was very unusual to find Roman properties survive in such a setting and be so complete.
He said: "What's remarkable about the discovery is that it has survived over 1,000 years in a currently occupied city. The only reason they have survived is because they are under a park that has never been built on."
The discovery was made after geophysics specialist David Staveley used radar equipment with the agreement of Mr Kenny, who felt Chichester's parks were the most likely place to find remains.
Following the results from the scans, Mr Kenny and the local archaeology society carried out a very small dig in Priory Park, and the findings were confirmed - leaving experts stunned.
Mr Kenny said: "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.
"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."
Experts believe the houses were originally located on a street, which has not survived as a reservoir was built in the park during the Second World War.
Intriguingly, the scans also revealed another Roman street running further east under Priory Park, but this will not be uncovered, Mr Kenny added.
"We are just going to focus our attention on the area south of The Guildhall building that is located in the park," he said.
The district council is now looking to seek funding to carry out a more detailed dig, and a bid is expected to go to the Heritage Lottery Fund.
It is hoped site tours will eventually be run to provide the public with more information as the dig progresses. But there are no plans to keep the remains on permanent display.
Mr Kenny said: "When the work has been completed it is more likely that we will return the ground to its current state.
"Instead, the likelihood is that we will create 3D imaging and information that will provide people with all of the information that they need in the long term."
In the centre of Chichester, Priory Park was given to the people of the city by the Duke of Richmond as a First World War memorial.
Councillor Susan Taylor, of Chichester District Council, said: "This discovery is very exciting and is of national historical importance."