Musicians who performed at Live Aid, the transatlantic concert that raised millions for famine relief in Ethiopia, reunited in London on Sunday to mark the event's 40th anniversary, attending a special performance of the musical "Just For One Day".

To mark the Live Aid anniversary, the BBC and CNN have co-produced a documentary series, “Live Aid: When Rock ’n’ Roll Took On the World.” It also covers Band Aid and Live 8, concerts that Geldof organized in 2005 that helped pressure the world’s richest countries to cut the debt owed by the poorest countries and increase aid spending.

Forty years ago, music history was made when simultaneous concerts in London and Philadelphia raised money for famine relief. Beyond the dollars, Live Aid supercharged how benefit concerts could make a difference.