It is estimated that over 50,000 stone megaliths were erected in a great arc around the coasts of Europe, from Sweden and the Shetland Islands in the north to Spain, Portugal and Malta in the south. No one knows when they were erected, who erected them, nor for what purpose they were erected. Dating them has not been easy, as they were cut from stone. Estimates put them around 4,500 years ago (2,500 BC)

The most famous megaliths are found at Stonehenge. They are located on the Salisbury Plain in southern England, a chalk grassland that stretches as far as the eye can see.