Stonehenge is a group of standing stones in southern England, dating back to 2000-1800 B.C. The reason for building Stonehenge is unknown but it is believed to have been a place of worship and ritual, such as a religious center, and also as an astronomical observatory. Two types of stones were used for the construction of Stonehenge. One type is known as the ‘bluestones’, which weigh almost four tons and were brought from 240 miles away. Other type of stone is the ‘Sarsen’ stones, which had a height of about 18 feet and weigh 25 tons.