Hundreds of solstice revellers have arrived near Avebury and spent the night partying.
Vans and cars are parked all along the Ridgeway above East Kennett and drums could be heard for miles around.
Police have now blocked access to that section of the Ridgeway, but cars and vans are parking along the A4 and in nearby villages and farm tracks.
Marlborough police say they have taken the difficult decision to prevent further access in order to maintain public safety and prevent potential damage to nearby farmland.
"This is in response to large numbers of people and vehicles in the area.
"Our officers are present and access is now closed, therefore we would advise people intending on travelling to the area not to do so."
Thousands of bollards have been placed preventing parking for a mile radius around the ancient site.
More crowds are expected today, ahead of solstice sunrise tomorrow morning (Monday June 21) at around 5am.
Last night's celebrations - an annual event around Avebury - passed off without incident, and bleary eyed revellers said the atmosphere was 'chilled' and 'really pleasant'.
The village of Avebury has more or less been cordoned off.
Idril, who has the title crone of Avebury, was walking her dog first thing this morning.
"We could hear the drums last night. There are a lot of vehicles up there on the Ridgeway. More than usual I'd say. It's a bit of a shame for the horse drawn people though as it looks like they can't get up there. they usually go quite far up, but the way looks difficult for them.
"I expect we will see more people here tomorrow for solstice."
Local pagan priests will perform their annual ritual of capturing the morning sun.
English Heritage will be live streaming Solstice celebrations from Stonehenge on their website on Sunday evening.
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