Short answers, pulled from the story.
The Indiana General Assembly named Indianapolis as the new capital city on the 6th of January 1821. The state government officially moved from Corydon to this location effective the 1st of January 1825.
Surveyors Alexander Ralston and Elias Pym Fordham designed a grid plan centered on a traffic circle. This layout radiated four diagonal avenues from the center including Indiana Kentucky Massachusetts and Virginia streets.
Fear turned to panic in July 1863 during Morgan's Raid though Confederate forces never reached the city limits. Union soldiers had previously disrupted a statewide Democratic convention at Pogue's Run on the 20th of May 1863.
Effective the 1st of January 1970 Unigov expanded the city's land area by adding surrounding townships to Marion County boundaries. This consolidation increased the population by approximately 250,000 people creating one of the first major city-county mergers without a referendum since New York formed in 1898.
Ray Harroun won the inaugural Indianapolis 500 race on the 30th of May 1911 at the newly completed speedway. The track holds 235,000 permanent seats making it the world's largest sports venue by capacity.