Indianapolis (), often shortened to Indy, is the state capital and most populous city of the U.S. state of Indiana and the seat of Marion County. According to 2017 estimates from the U.S. Census Bureau, the consolidated population of Indianapolis and Marion County was 872,680. The "balance" population, which excludes semi-autonomous municipalities in Marion County, was 863,002. It is the 17th most populous city in the U.S. The Indianapolis metropolitan area is the 34th most populous metropolitan statistical area in the U.S., with 2,028,614 residents. Its combined statistical area ranks 27th, with a population of 2,411,086. Indianapolis covers 368 square miles (950 km2), making it the 16th largest city by land area in the U.S.
Indigenous peoples inhabited the area dating to approximately 2000 BC. In 1818, the Delaware relinquished their tribal lands in the Treaty of St. Mary's. In 1821, Indianapolis was founded as a planned city for the new seat of Indiana's state government. The city was platted by Alexander Ralston and Elias Pym Fordham on a 1-square-mile (2.6 km2) grid next to the White River. Completion of the National and Michigan roads and arrival of rail later solidified the city's position as a manufacturing and transportation hub. Two of the city's nicknames reflect its historical ties to transportation—the "Crossroads of America" and "Railroad City". Since the 1970 city-county consolidation, known as Unigov, local government administration operates under the direction of an elected 25-member city-county council headed by the mayor.
Indianapolis anchors the 27th largest economic region in the U.S., based primarily on the sectors of finance and insurance, manufacturing, professional and business services, education and health care, government, and wholesale trade. The city has notable niche markets in amateur sports and auto racing. The Fortune 500 companies of Anthem, Eli Lilly and Company, and Simon Property Group are headquartered in Indianapolis. The city has hosted many international multi-sport events, such as the 1987 Pan American Games and 2001 World Police and Fire Games, but is perhaps best known for annually hosting the world's largest single-day sporting event, the Indianapolis 500.Indianapolis is home to two major league sports clubs, the Indiana Pacers of the National Basketball Association (NBA) and the Indianapolis Colts of the National Football League (NFL). It is home to a number of educational institutions, such as the University of Indianapolis, Butler University, Marian University, and Indiana University – Purdue University Indianapolis (IUPUI). The city's robust philanthropic community has supported several cultural assets, including the world's largest children's museum, one of the nation's largest privately funded zoos, historic buildings and sites, and public art. The city is home to the largest collection of monuments dedicated to veterans and war casualties in the U.S. outside of Washington, D.C.