Stonehenge built about 4000 years ago. It was a complex astronomical computer. It could be used to predict when eclipses would occur. 

The study of planets and stars has always been important to human beings in the stone age 20,000 years ago before calendars were developed, the movement of the stars was used to plan the sowing times for crops. Five thousand years ago, priests in middle east were making astronomical measurements. They could predict eclipse, and used their information for ceremonies and for astrology. 

Stonehenge 4000 years ago