Ryogoku is an area of Tokyo where the sumo stadium, many sumo stables, chanko restaurants and other sumo related sights can be found. It is the center of the sumo world.
Until the beginning of the 20th century, sumo tournaments were held outdoors at shrines and temples. In 1909, the first permanent sumo hall was built in the Ryogoku area, where outdoor sumo events had been held for a long time before.
The current Kokugikan is the fourth permanent sumo stadium built in Tokyo. It has been in use since 1985, and is located just next to Ryogoku Station. It seats over 10,000 visitors and hosts three of the six annual sumo tournaments (in January, May and September).
Sumo stables are the places where sumo wrestlers live and train. Among the several dozens of sumo stables currently in existence, many are located in the Ryogoku area. At some stables, it is possible to view the sumo practice in the early morning hours.
Chanko nabe is the staple food of sumo wrestlers. It is a hot pot dish that comes in many varieties and contains vegetables, seafood and meat. There are several restaurants in the Ryogoku area that feature chanko nabe on their menus.