Revellers celebrate the summer solstice at Stonehenge on Salisbury Plain in southern England yesterday. Stonehenge is a celebrated venue for festivities during the summer solstice – the longest day of the year in the northern hemisphere – and it attracts thousands of revellers, spiritualists and tourists. Druids, a pagan religious order dating back to Celtic Britain, believe Stonehenge was a centre of spiritualism more than 2,000 years ago.