Stonehenge is a prehistoric monument located in Wiltshire, England, constructed sometime between 3000 and 2000 BC. This week, researchers announced they had finally traced the origin of its giant sarsen stones to the West Woods, a forested area about 15 miles (24 km) away in the town of Marlborough. These massive stones, which make up Stonehenge’s central horseshoe, stand up to 23 feet (7 m) tall and weigh up to 30 tonnes.