Like a dark, glittering cathedral buried beneath the streets of London, the atrium to the Ministry of Magic is the largest set ever built for a 'Harry Potter' film. This setting for the film's climactic battle is a massive 210 feet long, and will be extended digitally to look even larger. 'It's an underground city, really,' says production designer Stuart Craig. 'It's absolutely cavernous.' The ministry is the hub of the wizarding government, the equivalent of our Capitol Hill. It had to look imposing. Rows of fireplaces, where witches and wizards arrive like commuters at Grand Central Terminal, are decorated with gold leaf, and Craig and his team covered the high walls and arches in dark green and red faux ceramic tile, similar to the real tile used in London subway stations in the early 1900s. 'They were very popular Victorian colors,' Craig says. 'Many people see them as heavy and oppressive, which they are.' But the curved offices (in the far back right of the photo) that look out onto the atrium had a more, uh, modern origin. 'I was driving by a Burger King at the bottom of Oxford Street and Tottenham Court Road--a pretty uninspiring place--and I looked up and there was this incredible Victorian façade of decorative brick work and protruding bay windows,' he says. 'That was the germ of the idea.'