The collapse of two of the tallest buildings in the world, the slamming of a plane into the… The collapse of two of the tallest buildings in the world, the slamming of a plane into the Pentagon and a plane crash in Somerset County disrupted the regular pulse of life in the city of Pittsburgh as businesses closed, buildings were evacuated and people scrambled to get in touch with friends and family. Several local businesses voluntarily evacuated their Downtown office buildings. According to the Pittsburgh Post-Gazette, the USX tower