Many Tokyoites will tell you that the best way to get to know their city is to travel station by station on the Yamanote Line. This commuter rail loop is one of Tokyo's original train lines -- it has been circling the city centre on raised tracks since 1925, and parts of the line are decades older. It is also the city's most iconic, with a long chain of silver carriages striped an unforgettable lime green. Millions of people ride the Yamanote Line every day. At peak hours, trains run every two minutes.

However, the Yamanote Line is more than just a train line; it effectively divides the city in two. What is inside the loop is downtown and what is outside is residential. What falls on the line serves as a gateway to both. As a result, the neighbourhoods along the loop count among the city's most developed. They also include many of Tokyo's famous sights: The Ueno neighbourhood, which is full of national museums; Akihabara, a favourite haunt of anime fans and gadget collectors; the youthful shopping districts of Shibuya and Harajuku; and Shinjuku, where the neon-lit nightlife strips are peopled until dawn.

The circuit also takes in some lesser-known areas. This is evident at street level: in the brand of convenience store, in the merchandise for sale and whether or not the telephone lines are buried underground. When Tokyoites tell you to get off at every stop, they are pointing you towards these in-between spots, where the tell-tale signs of daily life are not overshadowed by crowds, tourists, skyscrapers and beguiling lights. It is an invitation to look below the surface.

Examined up close, Tokyo is dramatically different north to south, east to west and even from station to station. Make the rounds of all 29 stations on the Yamanote Line and Tokyo no longer appears a cohesive city. It is a collection of self-contained towns, each with a train station instead of a town square.

Nippori, in the city's northeast corner, for example, is synonymous with old Tokyo. It has a classic, pre-WWII main street that, too narrow for cars, favours pedestrians, cyclists and, above all, shop owners, whose wares spill onto the street. Move a station or two beyond, heading counter-clockwise, and the scale of the streets becomes grander, the high-rise apartments more numerous. Go from east to west along the northern fringe of the line and Tokyo transitions gradually from the old city to the new, through squarely, sleepy middle-class neighbourhoods that are coloured by their proximity to the sprawling northern suburbs.

Due north, Sugamo, nicknamed the “Harajuku for grannies”, is something else entirely. While it does not have the tightly wound alleys and low wooden buildings of the old city, its heart is very traditional. Like Harajuku, Sugamo has a famous pedestrian shopping street, but its shops are popular with seniors instead of teens. There are old-fashioned Chinese medicine herbalists, traditional foodstuff vendors selling seaweed and glazed crickets by the handful, and more than a few shops hawking aka-pantsu -- bright red, high-waisted underwear believed to ward off evil and bring the wearer strength and vitality.  Kōgan-ji, a local temple, has long been believed to lessen the physical pains of those who pay their respects. Naturally it draws an elderly crowd (though not, of course, exclusively), and the shops simply followed.

As the train rounds the northwest corner, it passes the large transit hub of Ikebukuro, comparatively quiet Meijiro and the student haunt of Takadanobaba. “Baba” is home to Waseda University (one of Tokyo's best) and the requisite stew of cheap eateries, dive bars and used bookstores. It also lays claim to a particularly high concentration of ramen (noodle soup) shops; none of which offer a taste of student life better than Benten (3-10-21 Takada, Toshima-ku), where a “large” order gets you one kilogram of noodles.

Just one stop away to the west, the neighbourhood of Shin-Okubo shows off Tokyo’s rarely seen multicultural side. This is the city's “Little Korea”, where you can get hot tteokbokki (pounded rice cakes in chilli sauce) from the takeaway counter at supermarket Seoul Ichiba. Thai and Malaysian restaurants and shops can be found here too.

After Shin-Okubo comes Shinjuku, the west side's big divider in terms of wealth and prestige, especially among younger, fashion-conscious Tokyoites. South of this overwhelming commercial and entertainment centre, Tokyo begins to take on a more moneyed polish. While the change is not immediately obvious outside of Yoyogi Station, the first stop past Shinjuku, concrete evidence lies a few blocks away, at Yoyogi Village. This fashionable new development consists of cafes and boutiques housed in shipping containers arranged around a landscaped garden. It is a sign of what is to come.

From here, the train skirts along the wealthy southwest edge of the city, through neighbourhoods that less than 100 years ago were nothing but rice fields. Harajuku and Shibuya, with their wall-to-wall boutiques and department stores, are both shopping meccas for fashion-conscious teens. Ebisu, with its open-air, brick-and-mortar shopping centre Ebisu Garden Place draws more sophisticated shoppers. Meguro, whose main street is lined with houseware boutiques and antique shops, is known as Tokyo's design district.

The city's southern edge grows increasingly business-like from west to east. Going from Osaki through Gotanda to Shinagawa, the buildings become bigger and taller, more glass and steel than concrete. Shinbashi and Yurakucho, in the southeast quarter, represent the beating heart of “salaryman culture” -- that of the hard-working, hard-drinking, grey-suited company employee. Their haunts include smoky yakitori (grilled chicken skewers) stands crammed under the Yamanote Line tracks and raucous beer halls, like Beer Lion.

Heading north from Tokyo Station, the Yamanote Line traces the gradual lowering of the skyline though Kanda, Akihabara and Okachimachi to Ueno. The crowds of suits, too, become diluted with students in school uniform, bar hostesses in flashy dresses and labourers in overalls. Returning to the northeast corner of the city, the train passes through Uguisudani before winding back up to Nippori. And proving that no two stations in a row are alike, Uguisudani is notorious as the point of embarkation for some of Tokyo's seamier love hotels.

The article 'Seeing Tokyo along the Yamanote Line' was published in partnership with Lonely Planet.