5,000 years old Neolithic burial chamber with a huge 25 tonne capstone , one of the largest in the UK . The capstone was cut from larger limestone rock . Visible tapered grooves on two sides are the result of wooden wedges being hammered into man made holes , the wedge was then drenched in water to expand holes deep and wide enough to snap off chosen section . The Capstone is supported by flat and short megaliths which would have made getting a massive rock into position easier .
Capstone is 18ft/5.5m long by 15ft/4.6m wide .
Burial Chamber was originally buried beneath a mound of earth .
The tomb was excavated in 1908, human and animal bones , flint tools and pottery were among the finds .