Stonehenge’s altar stone was carried all the way from north-east Scotland. But how?

Transporting a six-tonne megalith nearly 500 miles to Wiltshire is quite a feat. How was it achieved 4,000 years ago?

Even by modern standards, John o'Groats to Wiltshire is a bit of a trek: nearly 500 miles, 13 hours by car or a 10-day walk - and that is without having a six-tonne block of stone in tow. So the revelation this week that Stonehenge's altar stone came from the north-east of Scotland prompts the question of how on earth this feat was achieved more than 4,000 years ago.

When you're trying to move something weighing six tonnes in excess of 750km, it is an enormous undertaking," said Prof Nick Pearce, a geologist at Aberystwyth University and the co-author of the research.