Most modern velodromes (special stadia built for cycle-racing) are indoor arenas featuring a steeply-banked wooden or concrete-surfaced track between 200 and 300m in circumference.
It is also possible to cycle indoors by using either a special stationary cycling machine (an exercise bike) or by placing a conventional bicycle on rollers. Such rollers are often used by racing cyclist during warm-up routines prior to racing events, or as a training option, perhaps when the weather is too bad to train outdoors.
Indoor track racing reached a peak of popularity in the 1930's in the US, when 6-day relay races were held in Madison Square Garden in New York. The word "Madison" is still used to describe a relay cycling race.