New transportation systems have always attracted attention of both transportation experts and general public: the first railway in England, first automobile and streetcar in Germany, first airplane in the United States - all of these inventions attracted excitement, curiosity, enthusiasm - and skepticism. With time, many inventions fulfilled or exceeded expectations: they have been developed into major transportation systems which influence our lives and shape our cities. However, an even greater number of inventions never developed into viable systems; incorrectly conceived, they never matured into operating systems. For the last 20-30 years there have been many inventions of automated transit systems. They attracted attention by their new vehicle and guideway designs, operating concepts, and new image. Among the numerous inventions there were many promising concepts, as well as misguided proposals. Parallel with these developments, understanding of urban transportation and analytical methodology for its evaluation have advanced greatly. A particularly important development has been system approach to urban transportation which allows evaluation of entire systems, including · all their physical and operational components, rather than only mechanics and body of vehicles. This theory now allows us to evaluate different systems and define their optimal role in urban transportation. The main subject of this presentation is Automated Guided Transit; let us first define this mode of urban transportation.