High Quality Content by WIKIPEDIA articles! The Illinois State Capitol, located in Springfield, Illinois, is the building that houses the executive and legislative branches of the government of the U.S. state of Illinois. The current building is the sixth capitol of the state since its admission as a state of the United States in 1818. The current capitol is in the architectural style of the French Renaissance. The capitol was designed by Cochrane and Garnsey, an architecture and design firm based in Chicago, Illinois. Ground was first broken for the new capitol on March 11, 1869, and it was completed twenty years later for a total cost of $4,500,000.