The building's older design utilizes thick masonry and gives the building added strength, which helped the building withstand the attacks and remain structurally sound. The building has thick, heavy masonry in the infill exterior walls, which encloses the building's steel frame. Brick, cinder, concrete and other masonry materials encase interior steel columns, beams, girders and other structural elements. The masonry allowed the structure to absorb much of the energy from debris hitting the building.[12] Nonetheless, the building had extensive damage to its east and south facades.[3] Underground cable vaults belonging to Verizon, along with other underground utility infrastructure were also heavily damaged from water and debris.[5][13]
http://en.wikipedia.org/wiki/Verizon_Building