Illinois' Most Expensive Home Is a $18.75M Mansion in Chicago's Gold Coast Neighborhood Illinois' Most Expensive Home Is a $18.75M Mansion in Chicago's Gold Coast Neighborhood On the market for $18,750,000, this massive mansion in Chicago's Gold Coast neighborhood is the priciest home for sale in Illinois. Kristine Hansen, provided by FacebookTwitterEmail It's now on the market for $18,750,000 and listed by Katherine Malkin of Compass. The prodigious price tag makes it the most expensive home for sale in Illinois. The six-bedroom, 8.5-bath property was designed to house the sellers’ art collection and accommodate their children when they were young, Malkin thinks the residence—with its lovely limestone and black granite—could attract a variety of buyers.