Stonehenge's huge stones could have been dragged into place using sledges greased with pig fat.
The lard-based approach when building the iconic monument in Wiltshire is a theory suggested by Newcastle University archaeologists.
It emerged after pig fat residue was found on pottery shards discovered at Durrington Walls, near Stonehenge .
The walls have a long association with feeding the hundreds of people who helped build the landmark.
New analysis has found the lard may have originated from bucket-sized dishes which may have been used for the collection and storage of tallow – a form of animal fat.
It could then have been used to lubricate the sledges as they dragged the monoliths into place - a mystery that has long baffled historians.
Dr Lisa-Marie Shillito, a senior lecturer in landscape archaeology at Newcastle University, said: "I was interested in the exceptional level of preservation and high quantities of lipids – or fatty residues - we recovered from the pottery.
"I wanted to know more about why we see these high quantities of pig fat in pottery, when the animal bones that have been excavated at the site show that many of the pigs were 'spit-roasted', rather than chopped up as you would expect if they were being cooked in the pots."
She said many unanswered questions remain about the construction of Stonehenge.
Although shrouded in mystery, it is generally accepted they were moved by human effort - with most theories believing the rocks originated from Wales.
More than 300 shards have been discovered at Durrington Walls and the fragments have been involved in a series of archaeological studies.
Until recently, there had been an assumption that the traces of animal fat on the pottery were related to the cooking and consumption of food, but the tantalising greased sledge theory has now emerged.
Stonehenge was built thousands of years before machinery was invented with heavy rocks, weighing several tonnes each.
Some of the stones have been linked to a quarry 140 miles away in Wales. Historians also think the stones may have been constructed in stages.
