In which city did Metallica form?

Metallica formed in Los Angeles.

The band began in late 1981 when Danish drummer Lars Ulrich placed an advertisement in the Los Angeles newspaper The Recycler seeking musicians interested in bands such as Diamond Head, Tygers of Pan Tang, and Iron Maiden. Vocalist and guitarist James Hetfield answered the ad, beginning the partnership at the center of Metallica's early history.

Metallica was officially formed on October 28, 1981. The early lineup developed around the Los Angeles metal scene, with bassist Ron McGovney and guitarist Dave Mustaine joining before the band established its classic early lineup. Its first live show took place in Anaheim, California, in March 1982.

Metallica later became closely associated with the San Francisco Bay Area, where it relocated and built an important part of its audience. That history creates the most common mix-up: San Francisco was crucial to the band's development, but Los Angeles is the accepted answer for where Metallica formed. The band's name came from a suggestion connected to Ron Quintana, who was considering names for a metal fanzine.