20 Years after People: After just 20 years in Houston's sub-tropical climate, bats and birds have colonized the interior. The bats drop guano which attracts insects. The plants and fungi growing there provides food for any herbivorous animals that come who will attract carnivorous ones and the carrion eaters. All of Houston's sport stadiums were kept at a steady 42 degrees farenheit, they now swelter to twice that much.
100 Years after People: Due to the dome atop the stadium being made of steel and lucite, a century of neglect causes the 180,000 lb dome comes raining down. The bats and birds that lived in the dome fly to safety. It is outlasted by the Reliant Stadium.