Metallica's 1991 album, commonly called The Black Album, stayed at number one on the Billboard 200 for four consecutive weeks.
The album debuted at the top of the U.S. chart after its release on August 12, 1991. Its opening week included 598,000 copies sold, and the record remained in the top position through a four-week run.
That result was especially notable because Metallica was a heavy-metal band making a major stylistic transition. The album's cleaner production and shorter, more direct songs expanded the band's audience without abandoning its heavy foundations.
The four-week run is separate from the album's much longer overall chart life. The Black Album continued appearing on the Billboard 200 for many years, making it one of the most enduring albums of the Nielsen SoundScan era.