On the western edge of Paris, at the end of the grand 'axe historique' that runs from the Louvre down the Champs Élysées and on past the Arc de Triomphe, rises the futuristic skyscraper business district known as "La Défense."
Its centerpiece is the thirty-story-tall 'hollow cube' monument/office building known as "La Grande Arche de La Défense." Built in time for the bicentennial of the French Revolution, it's covered in white Italian marble.
La Défense isn't done growing. Plans have been approved for the Hermitage Towers — a project designed by British architect Norman Foster. When finished, these twin towers will be the tallest skyscrapers in Europe.
It's worth leaving the historic core of Paris to come spend a few hours here — the pedestrian-only plaza beneath La Grande Arche can be a good place to watch rollerbladers, and in December hosts an open-air "marché de Noël."
Adjacent to the immense cube is the CNIT — a conference center that is also of architectural interest: it's the world's largest enclosed building under an unsupported concrete span. Under that span is a convention center, luxury hotel, and the "FNAC" — one of my favorite consumer-spots when I lived in Paris: think Best Buy and Barnes and Noble fused together, but with socialist origins! Culture made affordable for the literate masses...
Via metro (line 1) and RER underground express train (line A), you're just minutes from the old heart of Paris.