 The original 7 World Trade Center was 47 stories tall , clad in red exterior masonry , and occupied a trapezoidal footprint . An elevated walkway connected the building to the World Trade Center plaza . The building was situated above a Consolidated Edison power substation , which imposed unique structural design constraints . When the building opened in 1987 , Silverstein had difficulties attracting tenants . In 1988 , Salomon Brothers signed a long @-@ term lease , and became the main tenants of the building . On September 11 , 2001 , 7 WTC was damaged by debris when the nearby North Tower of the World Trade Center collapsed . The debris also ignited fires , which continued to burn throughout the afternoon on lower floors of the building . The building 's internal fire suppression system lacked water pressure to fight the fires , and the building collapsed completely at 5 : 21 : 10 pm , according to FEMA , while the 2008 NIST study placed the final collapse time at 5 : 20 : 52 pm . The collapse began when a critical internal column buckled and triggered structural failure throughout , which was first visible from the exterior with the crumbling of a rooftop penthouse structure at 5 : 20 : 33 pm . The collapse made the old 7 World Trade Center the first tall building known to have collapsed primarily due to uncontrolled fires , and the only steel skyscraper in the world to have collapsed due to fire . 
