Madrid Barajas Terminal 4
Designed by "starchitect" Richard Rogers, Madrid's huge Terminal 4 tries to break free of typical box-style construction by using a roof line of undulating ribs, which helped it win the 2006 Stirling Prize for architecture.
Terminal 4 comes with a strike against it: it's so long (especially when you include the integrated, but next-door Terminal 4S) that it can feel like it takes forever to get from gate to gate. But this is an unusually intelligently designed terminal: clear, color-coded signs group together directions for gates, and multi-level walkways reduce traffic on each individual level. Even when the terminal is full (and I've changed planes at peak times here), it never feels oppressively crowded, and you never get frustratingly lost or stuck waiting for buses the way you can in the design-before-function Charles de Gaulle airport outside Paris.
Read more: http://www.frommers.com/slideshows/825001-world-s-10-most-beautiful-airport-terminals#slide838686#ixzz4KHiZodfQ