Stonehenge
Later, around 2400 BC, the Stonehenge builders brought thirty huge grey sarsen stones (sandstone blocks) to the site. They 'dressed' (worked on) the stones and gave them mortice and tenon joints. They erected these stones in a circle 33 metres (108 ft) in diameter, with a ring of 30 lintel stones resting on top. They fitted the lintels together using another woodworking method: the tongue and groove joint. These stones serve as reminders of the lengths ancient civilizations went to, transporting them vast distances, in their quest to commune with the cosmos. They arranged the remaining bluestones in an inner circle. Each standing stone was about 4.1 metres (13 ft) high by 2.1 metres (6 ft 11 in) wide, and weighed about 25 tons.