At the time of the September 11, 2001 attacks, the Verizon Building was being renovated. The Verizon Building had been adjacent to 7 World Trade Center to the east and the World Trade Center's Twin Towers to the south, and when the three buildings collapsed during the attacks, the south and east facades were severely damaged by falling steel beams. The collapse of the World Trade Center causing partial collapses on some floor slabs close to the windows, though the building as a whole was not in immediate danger of collapse. Debris also sliced water mains, flooding the basements. As a result, underground cable vaults belonging to Verizon, along with other underground utility infrastructure, were heavily damaged from water and debris. The Verizon Building received only moderate damage because its thick-masonry design gave the building added strength. The masonry allowed the structure to absorb much of the energy from debris hitting the building, and damage was restricted mostly to impact points. Although no fires were observed in the Verizon Building, the ground-floor murals were damaged by smoke.