Sometimes I get really into learning about vestigial technologies and design standards. Like how ascii was originally designed for electronic typewriters and has the carriage return character for telling a typewriter to move to the beginning of a line. That's used to do terminal animations nowdays. Also I remember reading somewhere that the current american standard railway width was designed to allow two horses to stand side-by-side within a train car. Also the main streets in paris are the width of a french cavalry regiment from the 1830's so they could move through the city easier.