40 years ago, on July 13, 1985, musicians and activists Bob Geldof and Midge Ure pulled off a seemingly impossible feat: two simultaneous concerts, held on two different continents, featuring the biggest musical acts on earth — and all for a good cause.

Live Aid grew out of Geldof and Ure’s work organizing the recording of “Do They Know It’s Christmas,” a star-studded 1984 single that raised funds for the Ethiopian famine. The song stayed at the top of the UK charts for five weeks and raised £8 million, which far exceeded the musicians’ expectations — and made them begin to wonder what else they could pull off.