Cities are defined by their skylines — while Paris is composed mostly of low-rise apartment buildings, New York is a city of tall office towers. But London is a city in transition. On Tuesday, Boris Johnson, the mayor of the British capital, attends a "topping out" ceremony for one of London's latest skyscrapers in a city where tall buildings cause a lot of controversy.
Until recently, London has been a low-rise city.
Even now, a 12-story building is considered rather tall.
But a spate of new skyscrapers is raising questions about the kind of city London should be.
The newest entrant is a building Londoners have dubbed the "Cheese-Grater." It's an unfinished, 52-story steel frame that looks, well, like a cheese grater. One entire facade of the building tapers down to the street at such a sharp angle, it just calls out for a block of English cheddar. Once complete, it will be London's second-tallest building.
Nigel Webb of British Land, the developer, says the building is designed so its smaller top doesn't obstruct the view of St. Paul's Cathedral, built by Christopher Wren in the 17th century. The church is many blocks away, but views of the building from around the city are protected by law.
"Had we designed the building so that it was like a traditional tower going straight up, it would have actually clashed with the dome of St. Paul's," says Webb.
This gets at why skyscrapers can be so difficult to build in London: The city boasts centuries of architectural history, and some observers are very worried about its changing skyline.
"You know nowadays, the landscape of London is completely transformed — has somehow burst into a kind of small Shanghai," says Francesco Bandarin of UNESCO, the United Nations' cultural organization for conserving world heritage. "But these changes have limits."
Bandarin says London's new skyscrapers threaten another important, London landmark, the Tower of London, which sits right in the shadow of the city's new buildings. Built by William the Conqueror in the 11th century, the tower oozes British history: A couple of Henry VIII's wives lost their heads here; it's home to the Crown Jewels.
UNESCO designates the Tower of London an official World Heritage Site, and Bandarin says it has warned the British government about the new development around it.
"We see now that it's very difficult to perceive the tower as it was in its very long millenary history because of the existence of these high-rise buildings," says Bandarin.
The British government is in talks with UNESCO to preserve what's left of the area. But Paul Finch, a critic at Architects' Journal, is concerned by what he says is the implication that instead of just preserving views of the Tower of London, UNESCO is urging the city to protect what visitors see from it.
"The idea that we're going to start protecting views from these historic monuments and places is a form of madness," says Finch. "There is a danger of ending up with great swaths of a city, which cannot accommodate taller buildings."
Heated battles have already erupted. John Penrose, a former government minister for heritage in the U.K., is in favor of development. But he says The Shard — the tall, glass, spike-shaped building that now dominates the London skyline — was nearly scrapped because of conservationists' concerns over the Tower of London. And he has his own concerns.
"In the worst case," says Penrose, "UNESCO could withdraw the designation of being a World Heritage Site."
That's something the organization has done only once in Europe, when Dresden built a bridge UNESCO said degraded the views around the German city.
In London's defense, Edward Lister, the city's deputy mayor for planning, says all of the new high-rises are essential for London to maintain its status as a global financial center.
"UNESCO is taking a very, very black-and white-position, and I'm afraid life's not like that," says Lister. "You cannot allow development to be stalled in a city like this. London's grown by 600,000 people in just the last five years. And we will be over 9 million people before New York. That's the pressure that the city's under."
Nevertheless, London has come up with new guidelines as a result of the furor over the city's building boom. Known as "The London Plan," it protects more views across the city. But some tourists at the Tower of London look up at the surrounding walls of glass and kind of like it.
"I think it shows how beautiful time was back in the 11th century, and just how beautiful the new creations are now in the 21st century," says Vanessa Lawson, visiting London from the nearby town of Hastings. "You know we kind of have to accept changes and go with them really."
And even more change is on the way. London has just approved proposals for tall buildings within view of another World Heritage Site, the Houses of Parliament, and UNESCO is concerned.