Clumber House, the seat of the Dukes of Newcastle, was demolished following a devastating fire in 1938 - after which the surrounding parkland and estate in north Nottinghamshire passed to the National Trust.
The charity posted intriguing photos on social media showing that the outlines of the house's foundations have re-appeared in the last few days due to the extremely dry conditions.
Clumber Park has previously organised archaeological digs and geophysical surveys of the mansion site to establish where exactly the old rooms once stood - but the heatwave has helped to reveal the answers.
The house was originally built for the second Duke in 1768 and suffered at least three major fires before it was finally destroyed. The only parts of the building to survive were the billiard room, which is now a gift shop, and the Duke's study, which became part of a restaurant. The chapel, stable block and kitchen garden are also still standing and have been converted into visitor facilities.
All photos courtesy of National Trust - Clumber Park.