Rohm and Haas Corporate Headquarters National Register of Historic Places Listing

It looks like a sleek grid. When the chemical giant Rohm and Haas wanted a new home in the early 1960s, they tapped modernist master Pietro Belluschi to design a nine-story monument of concrete and glass right across from Independence Hall. Belluschi did not just build offices he built a giant advertisement. They used Plexiglas everywhere. Light fixtures, corrugated sunscreens, and even the dark, translucent wall panels utilized the company's signature acrylic plastic, showing off its commercial viability to a skeptical public. The concrete columns support a floating waffle-slab ceiling that still makes architects drool today.

Critics at the time worried the stark, modern box would ruin the historic vibe of Old City. But it did the opposite. As the anchor of the city's massive post-war urban renewal project, the headquarters proved that cutting-edge 20th-century design could live alongside 18th-century brickwork without stealing the show. It cost about $10 million back in 1964. The federal government added it to the National Register in 2007, recognizing it as a masterpiece of the International Style and a rare corporate gamble on Philadelphia's downtown core. A gamble that paid off.

Today, the building still stands tall on Independence Mall West, though Dow Chemical bought the company in 2009 and the interior saw some major renovations. It remains a preservation success. Architects still study those iconic bronze-colored aluminum sunscreens and the open plaza below. It represents a time when corporate America wanted to look forward, not backward, even when sitting right next to the birthplace of the nation.

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