<P> Soon afterwards, the north eastern section of the Phase 3 IV bluestone circle was removed, creating a horseshoe - shaped setting (the Bluestone Horseshoe) which mirrored the shape of the central sarsen Trilithons . This phase is contemporary with the Seahenge site in Norfolk . </P> <P> The Y and Z Holes are the last known construction at Stonehenge, built about 1600 BC, and the last usage of it was probably during the Iron Age . Roman coins and medieval artefacts have all been found in or around the monument but it is unknown if the monument was in continuous use throughout British prehistory and beyond, or exactly how it would have been used . Notable is the massive Iron Age hillfort Vespasian's Camp built alongside the Avenue near the Avon . A decapitated seventh century Saxon man was excavated from Stonehenge in 1923 . The site was known to scholars during the Middle Ages and since then it has been studied and adopted by numerous groups . </P> <P> Stonehenge was produced by a culture that left no written records . Many aspects of Stonehenge, such as how it was built and which purposes it was used for, remain subject to debate . A number of myths surround the stones . The site, specifically the great trilithon, the encompassing horseshoe arrangement of the five central trilithons, the heel stone, and the embanked avenue, are aligned to the sunset of the winter solstice and the opposing sunrise of the summer solstice . A natural landform at the monument's location followed this line, and may have inspired its construction . The excavated remains of culled animal bones suggest that people may have gathered at the site for the winter rather than the summer . Further astronomical associations, and the precise astronomical significance of the site for its people, are a matter of speculation and debate . </P> <P> There is little or no direct evidence revealing the construction techniques used by the Stonehenge builders . Over the years, various authors have suggested that supernatural or anachronistic methods were used, usually asserting that the stones were impossible to move otherwise due to their massive size . However, conventional techniques, using Neolithic technology as basic as shear legs, have been demonstrably effective at moving and placing stones of a similar size . How the stones could be transported by a prehistoric people without the aid of the wheel or a pulley system is not known . The most common theory of how prehistoric people moved megaliths has them creating a track of logs on which the large stones were rolled along . Another megalith transport theory involves the use of a type of sleigh running on a track greased with animal fat . Such an experiment with a sleigh carrying a 40 - ton slab of stone was successful near Stonehenge in 1995 . A team of more than 100 workers managed to push and pull the slab along the 18 - mile (29 km) journey from Marlborough Downs . Proposed functions for the site include usage as an astronomical observatory or as a religious site . </P>

Where did the stones at stonehenge come from