The school has been rebuilt on no less than a dozen separate occasions, following misguided experiments and catastrophic malfunctions.[4b] Many of the Engineers are Dwarfs. Some of them are renegades from the Dwarf Engineers Guild which frowns upon innovation and regards much of the Empire's new technology as a heinous break with ancient tradition. The Engineers School attracts inventors from all over the Old World and has provided the Empire with a number of experimental weapons such as repeating muskets and pistols, multiple-barrelled cannons, mobile battle-towers called War Wagons, and the formidable Steam Tank.[1a]