The really, really, really tall building is already so high that it exceeded building regulations and the capacity of its own foundations long ago. It finally begins to topple over even before the Delta IV Heavy starts its engines. Just as the rocket is about to lift off, the range safety officer calls a hold and the really, really, really tall building comes crashing down at terminal velocity, wiping out the entire launch complex, rocket included.
It's a draw!
Rock-paper-scissors-shoot, anything you want to do!