The Indianapolis Motor Speedway, located in Indianapolis, Indiana, in the United States, is the home of the Indianapolis 500 and the Brickyard 400.

It has existed since 1909, and is the original Speedway, the first racing facility so named.  With a permanent seating capacity for an estimated 257,325 people, and infield seating raises capacity to approximate 400,000. which makes it the highest-capacity stadium-type facility in the world.

Considered relatively flat by American standards, the track is a two-and-a-half-mile, nearly rectangular oval with dimensions that have remained essentially unchanged since its inception: four 1/4-mile turns, two 5/8-mile long straightaways between the fourth and first turns and the second and third turns, and two 1/8-mile short straightaways, termed "short chutes," between the first and second, and third and fourth turns.

A modern infield road course was constructed between 1998 and 2000, incorporating the western and southern portions of the oval (including the southwest turn) to create a 2.605-mile (4.192 km) track.  In 2008, the road course was modified to replace the southwest turn with an additional infield section, for motorcycle use, resulting in a 2.621-mile (4.218 km) course.  Altogether, the current grounds have expanded from an original 320 acres (1.3 km²) on which the Speedway was first built, to cover an area of over 559 acres (2.3 km²).  Placed on the National Register of Historic Places in 1975 and designated a National Historic Landmark in 1987, it currently remains the only such landmark to be affiliated with automotive racing history.