A new attraction offering 40-mile panoramic views of London opens today.
The Mayor of London Boris Johnson will officially cut the ribbon for The View from The Shard, a viewing gallery on the 72nd floor of Britain's tallest building.
However, a forecast of poor visibility could mean visitors don't get the spectacular views they're hoping for.
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Pictures of today's events unfolding following a major security incident at the Houses of Parliament.
At least two people have died after a knifeman brought terror to the heart of Westminster.
The Cobra committee brings together government ministers with senior officials of the emergency services and security agencies.