STONEHENGE, England (June 22, 2009)--Thousands of neo-Druids, New Age followers and the merely curious flocked to Stonehenge, beating drums, chanting and dancing on the longest day of the year Sunday.

The ancient stone circle at the prehistoric monument in southern England was the site of Sunday's annual ritual marking the northern hemisphere's summer solstice.

Police arrested about 30 people on charges including drug offenses, assault and drunk and disorderly conduct, but say the gathering was largely peaceful.

In May, archaeologists found evidence indicating that ancient pilgrims perceived the stones to have healing powers, and some assert that the structure was part of an astronomical calendar.

Still other experts think the huge stones were aligned by a sophisticated sun-worshipping culture.