Administratively, Seoul is divided into 25 districts (구 gu), each with an area and population comparable to a small city. The districts are then further subdivided into 522 sub-districts (동 dong). The Han river bisects the city, splitting it into two halves: Gangbuk (강북), the northern, more historical half, and Gangnam (강남), the southern, wealthier and more modern half. The sheer size of the city means that travelers to Seoul will find it difficult to locate a true "center" of Seoul; instead, Seoul is almost more like a collection of cities that happen to be bunched together, each with their own central business and commercial districts. The two largest core areas are Jongno/Jung in the north, and Gangnam in the south. For travelers with more time, there are many more, smaller centers and districts to be explored, such as the island of Yeoui-do and the college district of Hongdae/Sinchon. For the typical traveler, it would be useful to divide the city into the following areas: