Clubbers returned to the dancefloor for the first time since the pandemic began at a pilot event for 6,000 people.
Revellers, who all had to produce negative coronavirus tests, did not have to wear face coverings or social distance.
Club night Circus hosted The First Dance at the Bramley-Moore Dock warehouse in Liverpool on Friday.
Crowds packed the floor to dance shoulder-to-shoulder and some were seen hugging and kissing each other.
Others sat on friend’s shoulders for a better view of the stage where Circus founder and DJ Yousef, Lewis Boardman, Sven Vath, The Blessed Madonna and Jayda G entertained.
Fatboy Slim is among the acts due to perform on Saturday.
In the queue outside the venue, Liverpool University student Elliott Cause, 20, said: “I feel like this is a big moment for the UK.
“I feel like uni students have been struggling without this, I feel like this will do a lot.
“You can already see people are so up for it, the energy’s great.”
Sam Murphy, 20, who is from Belfast, said that after starting at Liverpool Hope University last September, he had the “worst freshers ever” because of coronavirus restrictions.
He said even tearing ligaments in his foot and having to wear a protective boot had not put him off attending the first club night since March 2020.
He said: “No chance – the first thing I said was give me a boot and let me out.”
Mr Murphy, from Belfast, said he had done a coronavirus test on Thursday and again on Friday morning and would take another in five days.
His friend Aodghan Fegan, 21, said: “I hope it all goes well and hope the Covid levels still stay low so there’s more events like this.”
Eighteen-year-old Leah Lawless said she and her friends had been waiting to return to clubs for around a year.
She said: “We are very excited. It’s been hard, it’s been boring, a bit sad, depressing and not the best.”
Sam Newson, the event producer, said the pilot was “vital” after the events industry had been “decimated” over the last year.
He said: “For the last 12 months, it has been a disaster.
“People have moved on, I’ve got colleagues who have lost houses, it has been incredibly hard and so to try and get this back up and running is incredibly important.”
He added: “I stood on stage early on and I had a little bit of a teary eye, I’m not going to lie, it is very emotional.
“Any event is special but with the amount of work that has gone into this and to be the first in the country in over 12 months, it is very special.”
Scientists will be looking to see whether crowds mixing and dancing indoors increases the risk of transmission of Covid-19.
Air quality and movement was also being monitored as part of a Loughborough University-led study to create clear guidance on how to design and operate non-domestic buildings to minimise risk.
The night is part of the Events Research Programme, which will also see crowds return to events including the FA Cup final and a music festival held in Liverpool’s Sefton Park.