Actually was released on 7 September 1987, cementing the Pet Shop Boys' place in pop royalty, coming just 18 months after their hugely successful debut, Please.
Actually contained a slew of timeless pop classics, including Rent, Heart and It's A Sin, not to mention their collaboration with Dusty Springfield on the peerless What Have I Done To Deserve This?. As if that wasn't enough, it also featured fan favourites King's Cross and Shopping - it was no surprise when it went on to sell over four million copies.
With Actually celebrating its 29th birthday later this year, we've discovered 25 things that you probably didn't know, actually.
Click on the first image below to begin the gallery.
A potential alternative title for Actually was Jollysight'. Chris Lowe explained that Jollysight, "was the name of a hotel we saw in Italy - so that, when people asked why, we could say because it's a jolly sight better than the last one..."
It's A Sin saw the Pets win the Best International Hit award at the 1988 Ivor Novello's for the second year in a row, following the success of West End Girls from Please in 1987.
Album opener One More Chance was originally released as the band's second single in 1984 and was co-written by Bobby O and Neil Tennant. The version on Actually was a re-recorded effort and featured extra music composed by Chris Lowe.
The Canadian 12" release of One More Chance saw the Pets share vinyl space with the artists Girly and Divine - the track was, in fact, based on a backing track that Bobby O had originally written for Divine.
What Have I Done To Deserve This? was the biggest hit of Dusty Springfield's career in the US - reaching No.2 on the Billboard Hot 100.
What Have I Done To Deserve This? was co-written with legendary songwriter, designer and director Allee Willis, who also co-wrote the Friends theme tune and Boogie Wonderland.
The video to Rent featured a woman being driven to King's Cross by a chauffeur, played by Neil Tennant. King's Cross was, of course, the title of the final song on the record.
The Mercury-nominated indie band Field Music recorded covers of Rent and Heart for a 2012 Record Store Day release, entitled Actually, Nearly.
The Latin section at the end of It's A Sin translates as: "I confess to almighty God, and to you, my brothers, that I have sinned exceedingly in thought, word, act and omission, through my fault, through my fault, through my most grievous fault".
The 'Uh uh oh oh uh' refrain in Heart features the vocals of Neil Tennant, Luciano Pavarotti and Prefab Sprout's Wendy Smith.
It Couldn't Happen Here featured orchestral arrangement by Angelo Badalamenti, who also worked with David Lynch on Twin Peaks, Blue Velvet and Mulholland Drive.
Heart was originally called Heartbeat, but was changed after Culture Club drummer Jon Moss founded the group Heartbeat UK.
Always On My Mind was released during the Actually period, but was not included on the album. The single liner notes had the phrase "not from the album, actually".
Always On My Mind was recorded for a Granada TV special to commemorate the 10th anniversary of Elvis' death. It was originally due to be the B-side to Rent, but Neil and Chris then decided it was good enough to release as a single in its own right just two months after the release of Actually - it become the Christmas No.1 in 1987.
Shopping featured Fairlight (sampler) programming by J.J. Jeczalik, a co-founder of Art of Noise, with Trevor Horn and Paul Morley. He later became an IT teacher, retiring in 2013.
It's a Sin is the only song, alongside West End Girls, that has been played on every Pet Shop Boys tour.
It Couldn't Happen Here was co-written with the legendary composer Ennio Morricone.
It's a Sin went to number 1 in nine different countries and is believed to be the biggest-selling European single of 1987.
Heart was originally going to be offered to Hazell Dean or Madonna, but the band ended up keeping it for themselves.
The video to Heart features a vampire played by Sir Ian McKellen, and was filmed in Slovenia.
It's a Sin has been covered by the metal bands Gamma Ray, Graveworm and The Crüxshadows.
Pet Shop Boys performed What Have I Done To Deserve This? with Lady Gaga at the 2009 BRIT Awards.
King's Cross included lyrics that appeared to refer to the King's Cross Underground fire of November 1987, but the song was actually released two months before the tragic accident.
Actually reached a chart high of No.2 in the UK, being kept from the top spot by Michael Jackson's Bad.
The end of the video for Always On My Mind features Joss Ackland muttering "You went away. It should make me feel better. But I don't know how I'm going to get through" - lyrics from What Have I Done To Deserve This?