The only high-rise designed by Eero Saarinen, the 38-story CBS headquarters in Midtown Manhattan, turned heads from the very start. Clad in black granite with aggressive diamond-shaped piers wrapping around all four sides, the building offered a muscular contrast to the ethereal curtain-wall office towers rising around it when it opened in 1965. Instead of employing a steel frame and resting lightly on pilotis or slender columns, it had a reinforced-concrete structure at its core and along its perimeter. Sitting directly on the ground, it emerged like a sharply chiseled mountain from a sunken plaza separating it from the city’s sidewalks. No wonder everyone called it “Black Rock.”