Retzer Nature Center was John and Florence Retzer’s retirement home. John purchased the original 90 acres from the Federal Land Bank in 1938. The Retzer’s immediately began restoring the degraded land with over 26,000 trees, shrubs, and flowers, many obtained from the Wisconsin Conservation Department. These plantings can be enjoyed today. In 1973, Florence Horn Retzer bequeathed her property to Waukesha County for park purposes. Her vision was "to conserve the scenery, natural life and wildlife, leaving the land unimpaired for the enjoyment of future generations."