Stonehenge, UK [Photo/Agencies]

Stonehenge is known as a circle of upright stones set within a circular earthwork. It is located about 2 miles west of Amesbury and 8 miles north of Salisbury, England, UK. As a prehistoric monument, it is believed to have been built between 3000 BC and 2000 BC, with a history of more than 5,000 years.

The largest stones are the ones situated in the center of the ring, which measure 8 meters (26.25 feet) in height and weighs a few dozen tons. The most incredible feature of Stonehenge is that several of the huge upright stones are still capped by another equally massive horizontal stone sculpture. Their construction remains one of mankind's biggest mysteries. The site and its surroundings were added to the UNESCO's list of World Heritage Sites in 1986. It is one of the most famous tourist sites in the world, attracting more than 1 million visitors every year.