Adjacent to Tower Bridge, across the water from the Tower of London, the Norman Foster-designed City Hall is the eco-friendly home of the Mayor of London and the London Assembly. Its strange, leaning-back design -- as if it's scared of the water -- has made the steel-and-glass egg one of the riverside's most recognizable structures. There's a visitor center with a giant walk-on floor photo of the capital where temporary exhibitions are held. The rooftop gallery has great views but is usually closed for private events -- call in advance.