Transwikied from http://lifeafterpeople.wikia.com/wiki/The_Pentagon
In the South East,the Pentagon stands as the HQ of the U.S. Army.The structure,looking like a pentagon from aerial view,was a target for the 9/11 terrorist attacks that destroyed the World Trade Center.The building has 4,200 wall clocks,according to Ripley's Believe it or Not.Now,how long can it last?
100 years:The wall clocks finally fall off the walls and soon, the lights also collapse. The interior is rotting away.
300 years:The walls are in good shape,but the roof is taking on pressure. Vines and rain have damaged it so it collapses, bringing down the parking lot. The rubble pushes apart the walls and the HQ of the United States Army crashes down, just like the Al Quada terrorist group wanted to do.