3 ms·Appears in 2312 by Kim Stanley Robinson.by akozak 7y agoAppears in 2312 by Kim Stanley Robinson.joshgel 7y agoThey move the whole city around the planet at 7mph!! 10/10 would recommendtaneq 7y agoSounds like Absolution Gap and/or a less annoying version of the Mortal Engines movie (please tell me the book was better than this)._jal 7y agoAlso features in Charlie Stross, Saturn's Children.