This issue focuses on 20th century masterpieces that have recently experienced restoration, conservation, renovation or extension. While Eero Saarinen's TWA Terminal (1962) was restored (by Gensler) and revived through its linkage to the new Extension, Paul Rudolph's Art and Architecture Building in Yale University (1963) was also restored (by Gwathmey, Siegel & Associates Architects), but carefully unified with its extension. After repeated repairs and additions, Louis I.Kahn's Yale University Art Gallery (1953) (by Polshek Partnership Architects) and Ludwig Mies van der Rohe's Crown Hall IIT (1956) (by Krueck + Sexton) are now both restored to its original design. Further projects include the Conservation of the Bauhaus Building in Dessau, the Conservation of the Solomon R. Guggenheim Museum and the Nestlé WellNes Center. Essays by Paul Needham and Ulf Meyer.