The hunt has begun for the cause of a massive blackout across Spain, Portugal and parts of France that halted trains, bank machines and traffic lights, in one of Europe's biggest ever power system collapses.

Electricity is pulsing through Spain and Portugal again after a massive outage knocked out power for the entire

Monday's unpredecented power outage left much of the Iberian Peninsula in the dark. We take a look at what operators did to get power back after the blackout. View on euronews