Although the skyscraper at 550 Madison Avenue is known best for the distinctive broken pediment at its peak—a postmodern flourish by Philip Johnson that earned the tower its “Chippendale” nickname—the building’s arcades at street level are more significant and affect circulation on the grid. Completed in 1984 by Philip Johnson/John Burgee Architects as AT&T’s corporate headquarters, the original design of 550 Madison incorporated one pedestrian arcade along Madison Avenue and another midway down the block between 55th and 56th Streets. Both arcades earned the building floor area bonuses under the zoning law, but one was arguably a more successful space than the other. Partially exposed to the air, the 60-foot-high arcade along Madison opened the building’s base to pedestrians and created a dramatic visual effect when seen from outside, but from inside, the vaulted spaces were dark and windswept. CY