A quarter in east Tokyo where you can literally buy anything that works with electricity, and, in most cases, you can get it there sooner than anywhere else (this is less true for computer equipment, but definitely for consumer electronics). "A couple of square miles" is vastly exaggerated, but for several blocks, almost every building houses nothing but stores for computers, games, home cinema and Hi-fi equipment, household electronics and similar stuff. One exit of the Yamanote Line station there is actually called "Electric Town". On Sundays, they close down the roads through Akihabara because there are too many people for the sidewalk to hold.