Megaliths
From around 5000 BCE, massive stone structures were erected across the world. Intended to be seen from great distances, the majority of megaliths (from the ancient Greek megas meaning 'great', and lithos meaning 'stone') are believed to have been used for religious rituals. Some, mainly in Turkey, Syria, Lebanon, Jordan and Saudi Arabia, probably related to farming.
The most famous and sophisticated surviving megalitic monument is Stonehenge on Salisbury Plain in Wiltshire, England (opposite), built in phases from around 3000 to 2000 BCE. Set in a precise stone circle, the giant stones are positioned with astronomical precision to align with rising and setting points of the Sun at specific times of year. The massive horizontal stone lintels and vertical posts are attached using the mortice-and-tenon technique, with carved protrusions on the uprights that fit neatly into slots on the lintels.
Reference: National Graphic