Stonehenge acted as a prehistoric art gallery as well as an ancient temple, according to new evidence.
A detailed laser-scan survey of the entire monument has discovered 72 previously unknown Early Bronze Age carvings chipped into five of the giant stones. All of the newly discovered artworks are invisible to the naked eye.
Of the 72 images revealed through the data analysis, 71 portray Bronze Age axe-heads and one portrays a Bronze Age dagger.
The "rock art" discoveries almost treble the number of carvings known at Stonehenge – and the monument's largely invisible art gallery now constitutes the largest single collection of prehistoric rock carvings in Southern Britain.
The laser-scan survey was carried out for English Heritage by a Derby-based survey company – the Greenhatch Group – last year. A subsidiary of York Archaeological Trust – ArcHeritage, also operating on behalf of English Heritage – then spent many months analysing and cataloguing the vast quantities of data.
The revelations are likely to be of huge importance to archaeologists' understanding of a key part of Stonehenge's life as a prehistoric temple.
It is known that, when the main phase of the monument was initially built in the middle of the third millennium BC, it was designed primarily as a solar temple, aligned on the midwinter and midsummer solstices.
But as Stonehenge evolved over subsequent centuries, the extent to which other religious functions were added is not yet known.
Certainly, in the period 1800BC-1500BC, vast numbers of individual monumental tombs were constructed in the landscape around Stonehenge. The carved axe-heads and daggers also belong to this enigmatic period – and may signify some sort of expansion or change in the great stone circle's religious function.
In Indo-European tradition, axe-heads were often associated with storm deities. It may also be significant that the vast majority of the carvings either face a nearby set of tombs (from roughly the same period) or the centre of Stonehenge itself. Rare evidence from elsewhere in Britain suggests that axe-head and dagger carvings could have funerary associations.
The laser-scan data shows that many of the axe-head images have exactly the same dimensions as up to half a dozen other images in the prehistoric Stonehenge "art gallery".
This in turn suggests that real axe-heads were being used as stencils to help produce the images. If that is the case, the largest axe-heads portrayed – up to 46cm long – depict objects which were far bigger than archaeologists have ever found and which must have been for purely ceremonial or ritual use.
The survey and analysis has also revealed how finely the stone surfaces were worked; that the entire prehistoric temple was constructed to be viewed primarily from the north-east.
This indicates it is likely that some sort of religious procession made its way towards that side of the monument, probably on mid-winter's and mid-summer's day.