DORCHESTER, ENGLAND—The Guardian reports that a flurry of monumental building activity appears to have taken place across southern Britain around 2500 B.C. This construction boom may have resulted in several massive ceremonial structures appearing in the course of just a few dacades. A new study of Mount Pleasant, a so-called "mega henge" enclosure in Dorset, produced 59 radiocarbon dates and suggests that three stages of the monument were built in less than 125 years—a much briefer window than previously thought. Researchers also believe the monument was completed only some 150 years before populations arrived in Britain from continental Europe with a range of new technologies and religious beliefs. Mount Pleasant is one of five known mega henges in southern England dating to the same period, including Stonehenge. Archaeologists believe these monuments hosted religious and ritual gatherings, and attracted visitors who traveled over great distances to attend. To read more about the archaeology of Neolithic Britain, go to "Epic Proportions."