Armed police will be on patrol at Stonehenge as thousands of people gather to celebrate the summer solstice.
Extra security measures have been put in place following the recent terrorist attacks in London and Manchester.
Wiltshire Police said the move was to "reassure the public that we are doing everything we can to keep them safe".
The Pagan Federation said it "sadly accepted" the need for such security measures.
About 12,000 people attended the Neolithic site last year to mark the summer solstice, which takes place tomorrow.
Visitors will only be allowed to bring small bags with them and are urged to only bring essential items.
"At Stonehenge there will be an increased number of officers and staff this year carrying out high-visibility patrols, and as a further precaution visitors may see armed police officers in the vicinity," said Supt Dave Minty from Wiltshire Police.
"I must stress that this is not due to any increase in threat or change in the intelligence picture surrounding the event or the county as a whole."
David Spofforth from the Pagan Federation said it was "very sad" that armed police were necessary.
"I am not saying I am welcoming this, I sadly accept it," he said.
"But you just have to look at the events such as at Finsbury Park, a peaceful religious gathering where people suffered so much by the actions of one hate-filled individual."
English Heritage said it hoped this year's solstice festival would be the "greenest solstice yet", by encouraging people to either car share or travel by public transport.
Parking charges of £15 have caused controversy though, after a senior druid challenged the fees in court.
King Arthur Pendragon lost his claim last month that the "pay to pray" rules breached his human rights.