Later this year, Elon Musk's private rocket company, SpaceX, will launch a test flight of what it claims is the most massive rocket in existence: the Falcon Heavy. It looks a little like SpaceX's standard rocket, the Falcon 9, with two other Falcons strapped to its sides.
Put another way, this one ship has the liftoff thrust equivalent of 15 Boeing 747s tied together and running at full power.