> Gare de Paris-Nord, the busiest train station in Europe, is planned to have a floor area of 120 000 m² after the next renovation. I couldn't find the number f

> Gare de Paris-Nord, the busiest train station in Europe, is planned to have a floor area of 120 000 m² after the next renovation. I couldn't find the number for the ground area, but it's obviously smaller than the floor area. Dulles airport, in Washington DC (a relatively small city by all standards), has an area of 47 km². That's 47 000 000 m², for the unaware. Meanwhile, its annual traffic (about 20M passengers) is approximately a fifth of the Gare du Nord (about 100M passengers). Not to detract from the point but Dulles is way oversized for its traffic (so's BWI). Paris-CDG, Frankfurt, Schipol, or Madrid carry near triple (or above in high-traffic years) the passengers in half to 2/3rds the surface. Heathrow moves more than triple on about 1/4th the surface (though it's rather unpleasant IIRC).