Stonehenge
How long did it take to build Stonehenge? Construction on Stonehenge lasted approximately 1,500 years and spanned several distinct phases between 3,000 B.C and 1,500 B.C. The site at Stonehenge grew and developed over a very long period of time and was not completed all at once by its builders.
Some of the stones have fallen or broken, but it seems clear that the circle was built in some way to chart the arrival of the longest and shortest days of the year. Stonehenge could therefore have been designed as a sort of monumental calendar, and a precinct where celebrations of the two solstices could take place.
Stonehenge's astronomical alignment remains one of its most remarkable features. During the summer solstice, the sun rises precisely over the Heel Stone and casts its rays into the center of the stone circle. And on the winter solstice, the sun sets in the exact same place.