A man who proposed to his girlfriend at the Shard has said he had no idea that Boris Johnson and a media pack would be on the observation deck at the same time.
When James Episcopou, 22, got down on one knee the moment was captured by a host of photographers.
The couple, from Epping Forest, Essex, got engaged moments after the Mayor of London cut a ribbon at the official opening of the highest vantage point in western Europe.
Mr Episcopou, a supervisor at John Lewis, said: "I've had it planned since July last year. When tickets first came out I thought I've got to buy them, it's the perfect place to propose.
"Laura means everything to me and I wanted to make her feel on top of the world.
"We had no idea the media were going to be there, but when we arrived we saw Boris Johnson and there were cameras everywhere."
When asked if the presence of the media made him even more nervous, he replied: "There was no doubt in my mind that I was going to do it.
"For Laura it's made the day even more special. When people plan a proposal they think 'how can I make it special?'. I managed to do quite a good job."
Miss Taylor, a 22-year-old accountant, said: "I had no idea he had planned it. I thought we were going up to look at the view.
"James asked me to come over to him because some photographers would like to take our picture. The next moment he was on one knee and proposing. I was so shocked. I said 'yes, definitely', but then I was speechless."
The proposal took place on level 72 of the Shard, just over 800ft (244m) above the capital.
Mr Johnson had earlier described London's tallest building as "a most amazing place".
He said: "I don't think there's anything in London like this.
"It's the closest thing to being in an airplane and looking down on London. But you can walk around, you've got complete stability.
"You can see all the bends in the river, you can see my office, you can see Buckingham Palace, you can see the whole thing for 40 miles around."
The Shard's architect, Renzo Piano, added: "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."
On a clear day visitors to the Shard, which towers over the city at a height of 1,016ft, are promised a spectacular view of the capital.
But visibility was restricted for the dignitaries, journalists and members of the public attending the launch because of wet and cloudy weather.
Some 4,800 people paid for admission today - at £24.95 for adults and £18.95 for children.
Visitors to the attraction, on floors 68, 69 and 72, are whisked up in two high-speed lifts in around 60 seconds.
On a clear day they will be able to enjoy a 360-degree view of the capital's skyline, from a platform almost twice the height of any other in the city. With the help of specially designed telescopes they can pick out London's landmarks in the streets below.