Think of Tokyo as a variety of neighborhoods scrunched together, much like the pieces of a jigsaw puzzle. Holding the pieces together, so to speak, is the Yamanote Line, a commuter train loop around central Tokyo, passing through such important stations as Yurakucho, Tokyo, Akihabara, Ueno, Ikebukuro, Shinjuku, Harajuku, Shibuya, and Shinagawa.
Hibiya – This is not only the business heart of Tokyo, but its spiritual heart as well. Hibiya is where the Tokugawa shogun built his magnificent castle, and was thus the center of old Edo.
Akihabara – Japan’s foremost shopping destination for electronic and electrical appliances, in recent years has also become a mecca for fans of anime and manga.
Asakusa – historically served as the pleasure quarters for old Edo. The street’s atmosphere alone makes it one of the most enjoyable places to shop for Japanese souvenirs.
Shinjuku – major transport hub and a bustling shopping district, the area is also known for its nightlife, especially in Kabuki-cho, one of Japan’s most famous — and naughtiest — amusement centres.
Harajuku – The mecca of Tokyo’s younger generation, Harajuku swarms throughout the week with teenagers in search of fashion and fun.
Ryogoku – sumo central! You can often see the giants as they stroll the district in their characteristic yukata robes.
Odaiba – the new district, constructed from reclaimed land in Tokyo Bay. One of Tokyo’s hottest dating spots.
The rest from NY Times, originally published Nov 2006.