on which floor is the observation deck?
On the 71st floor.
Chrysler Building
From the building's opening until 1945, it contained a observation deck on the 71st floor, called "Celestial". 
what is in the top of the chrysler building The terraced crown which is an extension of the main tower. where is the building located? It is located in the Turtle Bay neighborhood on the East Side of Manhattan, New York City, at the intersection of 42nd Street and Lexington Avenue near Midtown Manhattan.
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Chrysler Building [SEP] Observation deck
From the building's opening until 1945, it contained a observation deck on the 71st floor, called "Celestial". For fifty cents visitors could transit its circumference through a corridor with vaulted ceilings painted with celestial motifs and bedecked with small hanging glass planets. The center of the observatory contained the toolbox that Walter P. Chrysler used at the beginning of his career as a mechanic; it was later preserved at the Chrysler Technology Center in Auburn Hills, Michigan. An image of the building resembling a rocket hung above it. According to a contemporary brochure, views of up to were possible on a clear day; but the small triangular windows of the observatory created strange angles that made viewing difficult, depressing traffic.