The U2 album where the band started developing its signature sound, War coincided with the quartet's rise across the world. "Sunday Bloody Sunday" and "New Year's Day" revealed their political side, while "Two Hearts Beat as One" covered more personal matters. By the end of the decade, U2 would grow to gargantuan heights. The seed is planted here.

It has been seven years since U2 last released an album of new material — by far their longest hiatus. To put it another way, they released five studio albums — from Boy to The Joshua Tree — in the same time span.