From u2.com...
Summer 1985: Bono adds his vocal contribution to the recording of 'Sun City', a charity single to raise money for Artists United Against Apartheid organised by former Bruce Springsteen guitarist Steve Van Zandt.
Sun City was an entertainment complex created in the artificial Zulu 'homeland' of Bophuthatswana by the apartheid regime of South Africa. The idea was to woo top entertainers from Europe and America so that apartheid would benefit from indirect endorsement.
Steve Van Zandt, rhythm guitarist for Bruce Springsteen's E Street Band from 1975-1982, had visited South Africa on a fact finding tour in 1984 and had returned with the idea of a song could be sung by those who would refuse to play Sun City. This was recorded as a demo in the summer of 1985 and, shortly afterwards, was produced with a cast of star vocalists in the style of the recent charity singles for Band Aid ('Do They Know It's Christmas?) and U. S. A, For Africa ('We Are The World').
The single was produced by Van Zandt and Arthur Baker at Baker's Shakedown Studios in New York, with each singer performing all five verses individually before their key lines were mixed together in a composite version. Those who were on the East Coast at the time, such as Bono, Melle Mel, Darlene Love, Peter Wolf, Eddie Kendricks, Lou Reed and Bruce Springsteen, came to the studios. Those on the West Coast, including Bob Dylan and Jackson Browne, had tapes sent to them. Pete Townshend of The Who and forner Beatle Ringo Starr recorded their contributions in England.
The single 'Sun City' was a hit in Britain, America and Holland. It was banned in South Africa. Five versions of the song were included on the album of the same name.