The mosaics at one of Britain's most important Roman sites could be at risk unless £1m is raised by a public appeal.
The Cupid on a Dolphin mosaic is the most famous at the palace
A spokesman for Fishbourne Roman Palace, near Chichester in West Sussex, has said parts of the building have fallen into such a state of disrepair that the mosaics are now under threat.
Dating back to 43 AD, the site houses the largest in-situ collection of mosaics in Britain - of which the most famous is Cupid on a Dolphin.
The palace is considered to be one of the most important archaeological discoveries in the UK of the 20th century.
A £4m facelift is planned, with £2.5m already promised by the Heritage Lottery Fund and another £500,000 from local councils and archeological groups.
But The Sussex Archeological Society, which owns the site, has said a further £1m needed to complete the work must come from public and business contributions.
The money will pay for the refurbishment of the building protecting the mosaics, as well as a new visitor centre and conservation laboratory.
David Rudkin, director of the centre, said: "Since opening to the public we have welcomed over four million visitors.
Discovered by chance
"But not having any funds available for investment during that time means we are now facing considerable problems.
"We urgently need to undertake this work to protect the palace and its remains for future generations."
The palace is one of six buildings owned by the trust, which has donated £200,000 to the restoration project.
It was discovered by chance during the digging of a water main trench in 1960 and has been open to the public since 1968.
Archaeologists excavating the site have found it developed from a military base at the time of the Roman invasion of Britain in 43 AD.
By the end of the first century AD it had developed into a sumptious palace, with the mosaics found there among Britain's oldest.