Queen is celebrating the 40th anniversary of a landmark performance by releasing a live album recorded at the band's 1974 performance at the Rainbow Theatre in London.

Live at the Rainbow '74 is the audio recording from the band's March 31, 1974 performance when they were yet an up-and-coming act. Set to arrive on Sept. 9 in the United States, the forthcoming set will include over a dozen previously unreleased live performances. It will come in CD, Vinyl and standard DVD or SD Blu-Ray formats available as standard releases or special limited edition sets as well as digital formats, according to a press statement.

The band originally intended to release the live recordings as their third album, but they scrapped those plans to instead release new material. Although they later released a VHS recording of their two-night performance at the Rainbow from November 1974, the live audio from their first appearance had previously remained in the archives.

Deluxe versions of the new set will include audio from their November 1974 show on double-disc CD and double vinyl, as well as a super deluxe box set featuring a DVD, 60-page hardback book containing rare photographs and other various memorabilia.

Queen will kick off a new tour with Adam Lambert on June 19. Ticket and tour information can be found on the band's website. Further details on the Rainbow album can be found HERE.