The unique Post-Modern twin towers of Pennzoil Place presented several construction challenges: Contractors were faced with erecting a speculative office building resembling a 36-story double sculpture set into a glass pyramid at the base. And, in the middle of a business recession, pressure was on to rent the first few floors while the upper stories were still under construction. Thus, as the steel girders went up, the concrete walls were put in place behind them and the exterior curtain wall of double-paned solar glass was being hung as renters moved into the dramatic new building icon. In addition, soil conditions in downtown Houston required digging a block-square ultra-deep foundation. The eight-foot-deep concrete mat at the bottom is topped by three levels of parking garage and a lower level concourse linking Pennzoil Place to the Downtown Houston Tunnel System. Result: the first skyscraper project to radically change the Houston skyline and shape the future for Houston contractors.