Complex sentence: Silverstein won the bid when a deal between the initial winner and the Port Authority fell through, and he signed the lease on July 24,2001, just over a month before the towers were destroyed in the September 11 attacks.
Split into simpler sentences: Silverstein won the bid when a deal between the initial winner and the Port Authority fell through. Silverstein took control of the buildings on July 24,2001, seven weeks before the destruction of all seven World Trade Center buildings in the September 11 attacks.