A couple of years ago I was watching the demolition of a large Victorian building (Derby Carriage Works C Shop, for those who knew it).
The gable ends were brickwork about 500 mm thick and 15 m high, and the demolition excavator had to work very gingerly to bring it down piecemeal in the right place. Simply nudging near the apex caused the entire wall to flex to and fro quite alarmingly. Perhaps it was largely held in place by gravity.
Chris