Oklahoma City is 1,240 times larger than Grant Park (Chicago).
Area: 1 km2 calculated
Grant Park is a large urban park in the Loop community area of Chicago. Located in Chicago's central business district, the park's most notable features are Millennium Park, Buckingham Fountain, the Art Institute of Chicago and the Museum Campus. Wikipedia
Area: 1,682 km2 calculated
Oklahoma City is the capital and largest city of the U.S. state of Oklahoma. The county seat of Oklahoma County, the city ranks 27th among United States cities in population. The population grew following the 2010 Census, with the population estimated to have increased to 610,613 as of July 2013. Wikipedia