Famed as Houston’s first master-planned mixed-use development in the middle of an unzoned city, Greenway Plaza claims many construction firsts. The original four high-rise buildings were erected on a single pad. Within 18 years, 16 high-rise buildings were constructed in the area. The ten commercial buildings in the heart of Greenway Plaza range from 11 to 31 stories. Most are connected by a system of tunnels. The massive project also included a 3,500-car underground parking garage. Building it required the largest continuous concrete pour in Houston at the time.