I. On Salisbury Plain in southern England stands Stonehenge, the most famous of all megalithic sites. Stonehenge is unique among the monuments of the ancient world. Isolated on a windswept plain, built by a people without a written language, Stonehenge defies our imagination. The impressive stone circle sits atop a gently sloping hill on Salisbury Plain, around fifty kilometers from the English Channel. The stones are visible above the hills for a kilometer or two in all directions. Stonehenge is one of more than fifty thousand prehistoric “megaliths” in Europe. As you approach Stonehenge, the forty giant stones seem to touch the sky. Most of the stones are twenty-four feet or more in height. Some stones weigh up to forty tons. Others are smaller and weigh only five tons. At first glance, the stones may appear to be a natural formation. But a closer look shows that only human imagination and determination could have created Stonehenge.II. The Stonehenge of today is very different from the Stonehenge of old. Wind and weather have destroyed Stonehenge a little over the ages. People destroyed a lot more. Today, less than half of the original stones still stand as intended by their builders. Many formerly standing stones lie on their sides. Religious fanatics, who felt threatened by the mysteries posed by Stonehenge, toppled many of the standing stones. They overturned some of the enormous stones, which then split into pieces; they buried others. Other stones were “mined” over the centuries as free building materials and transported. Even in this century, visitors have come with hammers to take a shard of stone with them.III. Only in recent years have the stones been protected from the large number of people who see them each year. No one can walk among the stones anymore. Too much damage, intentional or not, has been caused by hundreds of thousands of visitors. Today, tourists are even prevented from walking among the stones, for fear that the millions of steps each year will make the stones unstable.IV. The 12th-century English writer and historian Geoffrey of Monmouth first recorded Merlin's construction of Stonehenge in his famous book History of the Kings of Great Britain. Geoffrey claimed that his book was a translation of "a certain very ancient book written in the British language". However, no other scholar or historian knows of the existence of such a book. According to Geoffrey, the large stones were brought from Ireland to England to mark the burial place of a group of murdered British princes..