Going underground at Maes Howe

"We can see what they did but have to experiment to find out how they did it."

At Maes Howe on the Orkney islands - a chambered tomb built around 3000BC - the builders devised a standard unit of length by taking detailed readings from the movement of sun and stars.

Dr Lomas believes this measurement - the megalithic yard - proves the islanders knew the earth was round.

They also understood that it moved around the sun centuries before it was generally accepted by the rest of the world.

Seafaring theory

The measurement was used to build state-of-the-art monuments, he said.

In the book Uriel's Machine: The Ancient Origins Of Science, Dr Lomas and co-author Christopher Knight argue that the megalithic yard - which measures 82.966cm - could easily have been taken by seafarers to Brittany and beyond.

The megalithic yard was first discovered in 1967 by Professor Alexander Thom, of Oxford University, who analysed more than 400 sites around the British Isles and Northern France.