The coins were found in a large storage jar
At least 10,000 coins believed to be from the Roman era have been uncovered in Shropshire.
Officials from Shropshire Council's Museum Service said the coins, thought to be from 320 AD to 340 AD, were found in a large storage jar.
They said the haul, found by an amateur treasure hunter, had been sent to experts in London to examine.
Councillor Stephen Charmley said it was the largest coin hoard to be found in the county in modern times.
The coins, which weigh more than 70lb (32kg), are thought to have been produced during the reign of Emperor Constantine.
They are all bronze and some have been silver washed.
Council chiefs said it was difficult to estimate the coins' value as they said there had been no comparable finds of that size.
A full report on the find will be compiled after the coins are examined by the experts.
Mr Charmley said he hoped the museum service would acquire the coins and put them on display in the new Shrewsbury Museum.
The council has not revealed where in the county the coins were found.