At which Los Angeles studio did Metallica begin recording The Black Album?

Metallica began recording The Black Album at One on One Recording Studios in Los Angeles.

The main recording sessions started in October 1990 and continued into 1991. The band also spent about a week recording at Little Mountain Sound Studios in Vancouver, British Columbia.

Final overdubs and mixing took place at A&M Studios in Hollywood during June and July 1991. This distinction matters because One on One was the principal starting location, while A&M was used later for finishing work.

The album's recording period was unusually demanding for the band. Metallica was working with Bob Rock for the first time, and Rock encouraged a more collaborative studio method. The sessions produced a slower, more polished sound than the group's previous thrash-oriented records.