In operation for more than 15 years, Window World is one of the largest window replacement firms in the United States. Located in Huntsville, Ala., the firm specializes in interior remodeling and home improvement services. It distributes a gamut of windows and doors, such as double hung windows, siding windows, patio doors and garage doors. The window firm carries a host of replacement windows and energy efficient windows. Additionally, Window World features a repair and maintenance service facility.