The band cited an art exhibition by victims of the atomic bombings of Hiroshima and Nagasaki that was held at The Peace Museum in Chicago as the lyrical inspiration for the song.

The song, like many tracks from The Unforgettable Fire, is an atmospheric composition, with ambient use of guitar and a string arrangement by Irish jazz musician Noel Kelehan.

The song evolved from a short piano composition that guitarist the Edge had written during a demo session with Jimmy Destri from the band Blondie.

[4] In late 1983, after completing their War Tour, U2 worked on material for their upcoming album The Unforgettable Fire at lead vocalist Bono's seaside home in a Martello tower in Bray, County Wicklow.

"[3][4] After bassist Adam Clayton and drummer Larry Mullen Jr. recorded a live rhythm section, the Edge said, "we knew we had something".

At that point, the song did not have a guitar part, as the Edge was still playing on the DX7 and Bono was experimenting with two dozen different vocal melodies.