Probably most of European will visit Tokyo Dome not for the main purpose. The main purpose is baseball games. It is the home of first professional baseball team in Japan, Yomiuri Giants. Concerts and other events are held when there is no baseball game on that day, even during baseball season.
Tokyo Dome is the first covered baseball stadium in Japan, opened in March 1988. Since then, four other covered baseball stadiums opened in Japan, Sapporo, Nagoya, Osaka and Fukuoka. All these cities are more than 1.5 million inhabitants It is located at former Korakuen velodrome. The velodrome itself was profitable but then mayor of Tokyo metropolis banned public gamblings in Tokyo. The velodrome was used as Korakuen Keirin.
Tokyo Dome was a replacement for Korakuen stadium which was located until 1987. Korakuen stadium opened in 1937, where Koishikawa arsenal was located. The name Korakuen comes from the adjacent garden, Koishikawa Korakuen which belonged Mito Tokugawa clan in Edo period.
Tokyo Dome is walking distance from Tokyo Metro and Toei subway Korakuen station and JR Suidobashi station. Please be aware the these two stations will be extremely crowded when baseball games and concerts are held. The maximum capacity of baseball game is 46000, concert is 57000.