Fox River Grove is a village in the Cuba Township of Lake County and the Algonquin Township of McHenry County, Illinois, United States. The population was 4,854 at the 2010 census.
In 1850, Frank Opatrny purchased 80 acres (320,000 m2) of land on the southern shore of the Fox River. The area gained a reputation with city dwellers as a vacation spot.In 1902, Opatrny built the Castle Pavilion, a luxury hotel which incorporated windows from the 1893 World's Columbian Exposition. Opatrny soon after bought approximately 100 additional acres in 1905 and erected several new facilities, including six bars, shooting and photo galleries, and a racetrack.In 1919, the village of Fox River Grove incorporated becoming the ninth Village in McHenry County.