Suitcases, boarding gates, and airport concourses are all designed to serve  a necessary purpose while saying something positive about travelers and the places they visit.

Terminals are the Taj Mahals of travel design. The best are gateways to  optimistic futures. Like a cathedral, the terminal’s colossal concourse inspires  a feeling of exaltation before sending you on your way. It is a locus of constant motion, and yet the traveler  is encouraged to pause for a plate of  raw oysters or a relaxing cocktail,  or to sit on a comfortable bench and gape at the terminal’s celestial ceiling, upon which the cosmos have been painted. The traveler needn’t take  notice of the building’s true genius:  its immensely intricate network of invisible thoroughfares and jetways spanning the distance from waiting gates to take-off.

At the dawn of the jet age, in the late 1950s, airports began to assume  a majestic scale, as if to affirm their new position as the world’s primary gateways. Building an airport was—– and still is—–an act of optimism and modernity, and mid-century designs reflected that. The symbolism of flight and movement as metaphors for  human progress became almost as  important as the logistical concern  for getting greater numbers of people on and off planes.

Eero Saarinen’s luxurious TWA terminal at JFK Airport in New York City perfectly embodies mid-century dynamism. Its graceful roof reaches outward like the stretched wings  of a gliding bird. Inside, its sweeping, curved lines, shafts of light, and free-flowing spaces are all carefully designed not just to suggest fluid movement but to churn foot traffic  in and out.

The rapid acceleration of global exchange in the 1990s inspired a new generation of airports, many in Asia,  to welcome and dazzle world travelers. Bold futuristic styles exploit extravagant building shapes made possible by advances in engineering. Near Seoul, Korea, Incheon International’s main passenger terminal is an amorphous beauty resembling a metallic jellyfish from outer space. Beijing’s striking new Terminal 3 projects a similar intergalactic confidence, at least when viewed from the air at night. The forthcoming terminal at Carrasco International in Montevideo, Uruguay, is a sleekly stylized update of the old flying saucer concept. All of these airports beg to be taken as messages from the future, reflecting upon the desires and intentions of the people who built them and shaping the impressions of the millions who pass through.

A more welcoming approach can be found in Richard Rogers’s exuberant interiors for the new Terminal 4 at Madrid’s Barajas Airport. The terminal is structurally familiar, but it is executed with a refreshing warmth and flair. There is nothing revolutionary in the terminal’s effective use of wood or in its vibrant, Almodóvaresque color scheme, but in the context of an airport it feels decidedly new. Here, the intent is to ease the transition from the air  to the actual place.

There will never be a final word on airport design, as airports are in a constant state of flux. New terminals are built in response to new complications, such as increased traffic and heightened security. Old terminals, no matter how beautiful, are continually modified. “To design a terminal, you have  to think ahead,” says Ripley Rasmus,  a design principal for HOK, who is currently involved in the new Indianapolis airport, the first new airport to be  built in the United States since Septem- ber 11, 2001. “But on a certain level,  all airports are construction zones.”