12 January 1969, Led Zeppelin's debut album was released.
It isn’t just the first album of a band that made history; it was a leap of faith that Jimmy Page and his crew made. Indeed, as Page said, because of the band had not yet signed their deal with Atlantic Records, he and Peter Grant (Zeppelin's manager) paid for the sessions entirely themselves.
This allowed ensuring artistic freedom at the band, as Page revealed in an interview:
"I wanted artistic control in a vise grip, because I knew exactly what I wanted to do with these fellows. In fact, I financed and completely recorded the first album before going to Atlantic ... It wasn't your typical story where you get an advance to make an album – we arrived at Atlantic with tapes in hand ... Atlantic's reaction was very positive – I mean they signed us, didn't they?”
(Interview with Jimmy Page, “Guitar World magazine”, 1993)
The album took only about 36 hours of studio time.
That was possible because of the material selected for the album had been well-rehearsed and pre-arranged by the band on Led Zeppelin's tour of Scandinavia.
Spiteful comments could be directed at insinuating that 36 hours is enough time for record a self-funding album.
By the way, although the album was not critically well-received at first sight, it was a huge commercially success and became a music milestone.