Wright was also an avid collector of Asian art and used Taliesin as a storehouse and private museum. Wright left Taliesin and the 600-acre Taliesin Estate to the Frank Lloyd Wright Foundation (founded by him and his third wife in 1940) upon his death in 1959. This organization oversaw renovations to the estate until late 1992 upon the founding of Taliesin Preservation, Inc., a nonprofit organization dedicated to preserving the building and estate in Wisconsin. The Frank Lloyd Wright Foundation and Taliesin Preservation operate numerous public programs on the campus, and the farm is still in use today by tenant farmers. The Taliesin estate was designated a National Historic Landmark in 1976, and the Taliesin structure was inscribed as part of a UNESCO World Heritage Site in July 2019. Four other Wright-designed buildings on the estate are National Historic Landmarks (but not part of the UNESCO designation, which is just reserved for the Taliesin structure). These are the Romeo and Juliet Windmill, designed by Wright in 1896; Tan-y-Deri, the home he designed for Jane and Andrew Porter, his sister, and brother-in-law, in 1907; the Hillside Home School, originally designed in 1901 for his aunts' school; and Midway Barn, a farming facility he began c. 1920. Location Jones Valley, the Wisconsin River valley in which Taliesin sits, was formed during Pre-Illinoian glaciation. This region of North America, known as the Driftless Area, was totally surrounded by ice during Wisconsin glaciation, but the area itself was not glaciated. The result is an unusually hilly landscape with deeply carved river valleys. The valley, approximately south of the village of Spring Green, Wisconsin, was originally settled by Frank Lloyd Wright's maternal grandfather, Richard Lloyd Jones. Jones had emigrated with his family from Wales, moving to the Town of Ixonia in Jefferson County, Wisconsin. In 1858, Jones and the family moved from Ixonia to this part of Wisconsin to start a farm. By the 1870s, Richard's sons had taken over operation of the farm, and they invited Wright to work during summers as a farmhand. Wright's aunts Jane and Ellen C. Lloyd Jones (known as Jennie and Nell) began a co-educational school, the Hillside Home School, in the family valley in 1887 and let Wright design the building; this was Wright's first independent commission. In 1896, Wright's aunts again commissioned Wright, this time to build a windmill. The resulting Romeo and Juliet Windmill was unorthodox