In the age of Google, the human memory doesn’t need to be what humans once needed it to be. So when Google fails… that’s a problem. My problem: I suddenly remembered reading an online discussion, some years back (anywhere from maybe 7 to maybe 19 years back), of the tallest building possible. The context was the nutty idea of using it as a launch pad for a space rocket, and someone mentioned that the USAF (?) had asked an aerospace company (General Dynamics?) to do a study just to see if it was possible. My *vague* memory has it that the answer came in the form of a lightweight carbon fiber structure shaped like a pyramid, something on the order of 10 kilometers tall. But buggered if I can find a single reference to this idea. Does this sound familiar to anyone?