About 21,000 revellers gathered at Stonehenge in Wiltshire overnight to mark the summer solstice.
The 5,000-year-old World Heritage site was open to the public, following earlier years in which it was closed amid fears of damage to the stones.
Some 150 police were on site this year, and a number of people were arrested for climbing on the stones and other offences, a BBC correspondent said.
Misty skies had obscured the 0458 BST sunrise for about 30 minutes, she said.
Other years have seen battles between police and revellers, including the infamous 1985 encounter, dubbed the Battle of Beanfield.
A violent confrontation between 300 people who wanted to reach the stones and the police saw 12 people hospitalised.
This year police issued several warnings and said anybody going to the site was liable to be searched.
The constabulary added that traffic on the A303 and A360 next to the site was expected to be very busy during Monday morning.
English Heritage, which looks after the site, also issued strict rules. Those attending were only allowed a small amount of alcohol for personal use.
And only acoustic instruments were allowed.
Inside the ring, thousands packed around groups of drummers and other musicians while some took the opportunity to sprawl on the ancient stones normally beyond public reach.
But the focus of the activity was on an impromptu open-air dance next to the famous Heal Stone, the marker for sunrise on summer solstice.
Druid leader “King Arthur Pendragon” presided over the festivities standing amid a ring of flaming torches overshadowed by a pair of giant horns, lit by burning branches.
“King Arthur”, who adopted the name in 1986 to denote his position as “Battle Chieftain of the Council of British Druids”, said the festivities marked the imminent arrival of dawn.
He said: “The fire symbolically welcomes the sun for the longest day of the year, part of the seasonal wheel which we as druids and pagans celebrate.
“It’s not a day in church for us, it’s a celebration, we don’t sit in pews.”