Archaeologists restoring a 17th Century castle in Derbyshire believe they may have uncovered Britain's first bathroom built after the Dark Ages.
The "baths" are thought to date to after the civil war
Repair works at Bolsover have unearthed remains built after the fall of the Roman Empire.
Two chambers - one thought to be a boiler room to heat bath water - are thought to date after the collapse of cleaning habits in the Middle Ages.
They were found in an abandoned outbuilding at the castle.
Sir William Cavendish (1593 - 1676) started the fashion for "bathing rooms" at the castle on returning to England after the Civil War.
He was exiled to the continent following Oliver Cromwell's victory but is thought to have brought back his Parisian washing habits to the UK after the restoration of Charles II to the throne.
Experts believe it may have had other uses as well.
John Burditt, of English Heritage, which is restoring the castle, said: "We are finding more out about Sir William Cavendish and his use of the castle.
"A lot of the rooms were used for dalliances of various kinds."
Sir William, who had five children by his first marriage, is thought to have introduced the baths to help his second wife, Lady Madge, in conceiving.
"Immersion in warm water was thought to be a way of treating infertility at the time," said Mr Burditt.
"Cavendish had the resources and room to make this possible on a large scale."