(1930 BC to 1600 BC) Soon afterwards, the northeastern 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. After the monument (1600 BC on) 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 known as Vespasian's Camp (despite its name, not a Roman site) 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. Function and construction Stonehenge was produced by a culture that left no written records. Many aspects of Stonehenge, such as how it was built and for what purposes it was used, 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. 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. The most common theory of how prehistoric people moved megaliths has them creating a track