The Mayor of London cut a ribbon just over 800ft above the capital to welcome visitors to the highest vantage point in western Europe.
He was joined on level 72 of London's tallest building by its architect, Renzo Piano, for the opening of the attraction, The View from The Shard.
Mr Piano said: "This building is magic for a number of reasons."First, because it's in London, second, because it's so tall, and third, because this building is a part of London. It's a sense of London."It's sad when London is sad, it's joyful when London is brilliant and joyful."
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Mayor of London Sadiq Khan is backing the scheme.
A spokesperson said the lightning strikes had left the "aircraft fuelling system unavailable."
Nearly 1,000 properties have been left without power, and road users have been warned of potentially hazardous conditions.