Designed in 1960 and completed in 1965, the CBS corporate headquarters, known as Black Rock, was New York’s first concrete office tower. Architect Eero Saarinen envisioned a sober granite-clad monolith – rising from a sunken plaza on a full Midtown block on Sixth Ave. from 52nd to 53rd streets – a form that contradicted the modernist paradigm of the gleaming glass boxes of Park Avenue. The engineer Paul Weidlinger likewise defied the standard approach of steel-frame construction and proposed a structure of reinforced-concrete columns, based on his experience in Washington DC and his background in France and Bolivia.