U2's Bono and The Edge Give Private Concert in Berlin Subway

Bono U2
Amy Harris/Invision/AP

Bono of U2 performs at the Bonnaroo Music and Arts Festival on June 9, 2017 in Manchester, Tenn. 

The exclusive fan event, on Berlin's U2 subway line, was to promote the band's 'Songs of Experience' album.

Bono and The Edge surprised local fans in Germany Wednesday by giving them a private concert on board Berlin's U2 subway line. 

Some 200 fans were on board a private train hired by label Universal Music to an exclusive meet and greet event to promote U2's new album, Songs of Experience. But they weren't told the band's singer and lead guitarist would be among their fellow straphangers. The Irish musicians jumped on board at one of the train's scheduled stops and rode with the group to Deutsche Oper station, where they performed an acoustic set of songs from the new album.

The U2 subway line, short for U-Bahn 2, has been in operation since 1966. U2, the band, also has a history in Berlin. The group recorded their legendary Achtung Baby album in at Hansa Studios near the newly-opened Berlin Wall in October 1990.

Songs of Experience, which dropped Dec. 1, via Interscope Records in the U.S., is on track to become U2's eighth No. 1 album on the Billboard 200 chart. Industry forecasters project sales of more than 170,000 equivalent album units in the week ending Dec. 7.

Songs of Experience is a companion album to the band’s last studio effort, 2014’s Songs of Innocence. Songs of Innocence was initially released as a free download exclusively through Apple’s iTunes program on Sept. 9, 2014. It was commercially released on Oct. 14 and sold 28,000 copies in its first tracking week of sales, peaking at  No. 9 on the Billboard 200. Both album titles are a tip of the hat to William Blake's collection of poems Songs of Innocence and of Experience.

This article originally appeared for The Hollywood Reporter.