More than 30,000 Roman coins were found by archaeologists working in Bath in 2007, it has been revealed.
The silver coins are believed to date from 270AD and have been described as the fifth largest UK hoard ever found.
The coins are fused together and were sent to the British Museum. Conservators are expected to take at least a year to work through them.
A campaign has now been started at the Roman Baths to try to raise £150,000 to acquire and display them.
The size of the find is not as large as the Frome Hoard in April 2010 when more than 53,500 coins were discovered by metal detectorist Dave Crisp near Frome in Somerset.
The coins found in this hoard date from a similar time and are thought to be the largest ever discovered in a Roman town in the UK.
Roman Baths spokesman Stephen Clews said: "We've put in a request for a formal valuation and then hope to buy the coins to display them at the baths.
"At the time there was a lot of unrest in the Roman Empire so there may be some explanation for why the coins were hidden away.
"The find is also unusual as it was discovered by professional archaeologists as opposed to an amateur using a metal detector," he added.