A seemingly curious alliance of druids, pagans, hippies, local residents and tourists gathered around Stonehenge and greeted sunrise on Wednesday, which is the longest day in the Northern Hemisphere.

Supporters say the tunnel will reduce noise and hide cars for visitors to the prehistoric landmark. Opponents warn of possible damage to the site which archaeologists continue to study.

The massive prehistoric structure "is significantly larger than any comparative prehistoric monument that we know of in Britain, at least," a lead researcher in the project says.