Municipal government serving The City of Lake Forest, Illinois. Established by charter in 1861, Lake Forest is a city located in Lake County, Illinois, United States. As of the 2010 census it had a population of 19,375. The city is located along the shore of Lake Michigan and is a part of the Chicago metropolitan area known as the North Shore. Lake Forest was founded around Lake Forest College and First Presbyterian Church. It was laid out as a town in 1857 as a stop for travelers making their way south to Chicago. The Lake Forest City Hall, designed by an architect named Frost, was completed in 1898 and originally housed the fire department, the Lake Forest Library, and city offices.