http://www.forbes.com/sites/rachelhennessey/2012/09/26/the-graying-of-modernism/
Humans are not the only creations that age. A handful of both distinguished and lesser-known creations of mid-century modernism turn 50 this year (Virginia’s Dulles Airport, Des Moines’ American Federal Building, L.A.’s Design Center). Because of their half-century age, such structures are eligible for protection under the National Register of Historic Places. [...]