“Convenience at its Best”
It is a lot stretch of halls and passages that connect all throughout the city. You can get to any train from any entrance. There are many shops and places to eat. There is probably at least one of each shop, considering that both sides are lined with shops; from clothing, to books, food, and nick-knacks.
It is a great way to get around (especially in the winter, fall, and the summer typhoon season) because it does all around the main part of the city and it is heated. You can stay out of the bad weather and still do everything you wanted to do that day. Most entrances even have an elevator, so even if you are carrying suitcases, or even just boxes, it is convenient.