It began the day after Jimi Hendrix died in 1970, with a mere 1,500 attendees and a fee of just £1 - including free milk from the farm.
Forty five years on, we take a look back at the most memorable performances to grace Worthy Farm.
With some complaining that the line-up was middle-aged when it was announced, Blur discarded any concerns of dullery when they closed Glastonbury 2009.
Their hit-laden set was praised for mixing up-tempo numbers such as Girls and Boys to slow and soulful This is A Low. And of course Phil Daniels popped on stage for their cockney classic Parklife.
It was the fourth time they'd played the festival, and their exhilarating 2009 set even saw an emotional Damon Albarn crying after To the End. A true blur of emotion, energy and nostalgia.
After the Stone Roses cancelled at the last minute, Pulp filled in to headline the festival. They were even booked so late that they were forced to camp as all the local hotels were full.
Having played a year before with a successful performance, the release of Common People really solidified their place as headliners and made for an era-defining moment in Brit Pop history. Jarvis Cocker famously took a photograph of the crowd from the stage - and has since shared his regret at losing the picture.
Just 11 days after releasing their critically acclaimed album Ok Computer, Radiohead stormed Glastonbury in 1997. They've since spoken out about the technical problems at the beginning of their set resulting in them believing it hadn't gone very well, but it's widely regarded as a seminal performance in the history of the festival and pivotal point in their career.
They played again in 2003 and allegedly turned down a spot in 2008 as Thom Yorke said the festival didn't have environmentally friendly public transport systems in place. Nevertheless, their 1997 set was voted the greatest ever Glastonbury headliner in a 2010 poll.
Paul McCartney (2004)
With more sing-along hits than you can shake a stick at, 70 year-old former Beatles member headlined a watery Glastonbury 2004 - with a two-and-a-half hour set. The gig was the final date on Sir Paul's world tour, ending with thousands singing along to Hey Jude. It set in stone his position as the most successful songwriter in the history of pop. Never have a load of 'na na na's' been so utterly enjoyable.
David Bowie (2000)
First performing at Glasto on its second year in 1971 - back when it was free to get in - Bowie returned to headline the festival in 2000 to a rapturous reception. Afterwards, event founder Michael Eavis labelled it the best Glastonbury ever.
He was reportedly asked to play for 2010's festival, but the appearance would have been Bowie's first concert in six years, since he suffered a heart attack while on stage in 2004. The 66 year-old is back on top form, as his new album The Next Day shot straight to number one earlier this year.
Jay Z (2008)
A controversial inclusion for some...
After Michael Eavis' shock decision to sign rapper Jay Z for the 2008 festival, there was a negative response from the public, with Noel Gallagher chipping in that there was no place for hip-hop at Glastonbury. Jay Z's cheeky comeback involved covering the Oasis hit 'Wonderwall' as his first song.
Many blamed the poor ticket sales that year on the choice to have a rapper as a headliner, but many said all doubt was allayed when his set failed to let the crowd down. When he won the Best International Male award at the Brits that year, he even thanked Glastonbury in his acceptance speech. Came, saw, conquered.
Muse's 2004 set was particularly poignant, as drummer Dominic Howard's father tragically died backstage after their performance.
It's been voted the greatest ever Glastonbury performance by NME readers, with organiser Emily Eavis commenting “People were sceptical initially...it really blew people's minds.” Their grandiose set was praised for the theatricality, ending with Plug In Baby - which was also voted as having the greatest riff of the decade.
What Jay-Z did for bringing hip-hop to the festival scene in 2008, the Hartnoll brothers did for dance music in 1994. Despite some rockier revellers wondering when the guitars were being brought out, the 40,000-strong crowd truly embraced Glastonbury's nod to the burgeoning nineties rave scene. And Orbital certainly didn't look back as they returned to play several times after.
The Smiths (1984)
Their addition to the line-up in 1984 sparked a heated debate among die-hard Glastonbury fans who didn't think the band belonged at the mellow festival. Guitarist Johnny Marr said 'Previously, we'd always played to manic, devoted audiences who were more like supporters at a cup final, but at Glastonbury we were playing to people who largely hadn't seen us before.' With Morrissey encouraging a rock n roll stage invasion in the days before barriers, the band stole the show and it was widely regarded as a turning point for Glastonbury.
Taking the place of The Kinks after they pulled out, T Rex made their name at the very first year of Glastonbury. The now less-famous Blues festival at the Bath & West Showground had inspired Michael Eavis start up a festival on a smaller scale, and he now considers this performance in his own personal top five favourite performances at Glastonbury ever. Will any performances from 2015 squeeze into his top spots?