Complex sentence: Demolition of the 1963 building began in July 2008, and by of September 2008, the Venable Gymnasium and the athletic locker rooms, band room, and chorus room located underneath it had been razed.
Split into simpler sentences: Demolition of the 1963 building began in July 2008. By September 2008, the Venable Gymnasium and the athletic locker rooms, band room, and chorus room located underneath it had been razed.