Wikipedia describes the concert:
The Beatles’ rooftop concert was the final public performance of the English rock band the Beatles. On 30 January 1969, the band, with keyboardist Billy Preston, surprised a central London office and fashion district with an impromptu concert from the roof of the headquarters of the band’s multimedia corporation Apple Corps at 3 Savile Row. In a 42-minute set, the Beatles played nine takes of five songs before the Metropolitan Police asked them to reduce the volume. Footage from the performance was used in the 1970 documentary film Let It Be.