The Edith Farnsworth House is a historic house museum along the Fox River near Plano, Illinois, United States. Completed in 1951, it was designed by Ludwig Mies van der Rohe in the International Style and built as a weekend retreat for the nephrologist and physician Edith Farnsworth. It is one of three private residences Mies designed in the U.S. and is cited as a major modernist work. The house is raised 5+1⁄4 feet (1.6 m) above the ground, with a minimalist exterior and a mostly open plan interior. It is the main building on a 62-acre (25 ha) estate that also includes a visitor center and exhibit gallery. The estate is owned and operated by the National Trust for Historic Preservation.

Farnsworth bought the site in the mid-1940s and asked Mies to design a house there after meeting him in 1945. Despite flooding concerns, Mies decided to build the house elevated above the Fox River floodplain. After extensive delays, work began in 1949, and Farnsworth moved in during December 1950. Mies and Farnsworth's once-cordial relationship deteriorated over the project's cost increases, and they sued each other in 1951, prompting a years-long legal dispute. Though the original design had numerous flaws and struggled to be energy efficient, Farnsworth owned it until 1972. The next owner, the British nobleman Peter Palumbo, renovated the Farnsworth House and used it as a summer retreat. After two floods in the late 1990s, Palumbo restored the house again, opening it to the public in 1997. The National Trust acquired the house in 2003 and reopened it the following year. Landmarks Illinois initially operated the house, which was renovated again following a 2008 flood. The National Trust took over operations in 2010.

The Farnsworth House is accessed from the south by an outdoor travertine terrace, occupying an intermediate level between the ground and the house itself. The concrete floor and roof slabs are supported by eight steel columns, which divide the house into three west–east bays. The facade is composed of glass, interspersed with steel mullions; the western third of the house is an open-air veranda. The interior has a minimalist color scheme and is interrupted only by an off-center utility core and a movable wardrobe. The core contains utilities, a kitchen, and bathrooms, while living, dining, and sleeping areas are placed around it. Radiant heating, pipes, and ducts were embedded into the floor, and both Farnsworth and Palumbo furnished the house with various items.

The Farnsworth House has received extensive architectural commentary over the years, with a number of laudatory reviews when it was built. Although it was initially controversial, in part because of its then unique modernist design and because of Mies and Farnsworth's feud; such criticism became less intense after Mies died in 1969. The house has been the subject of books, films, exhibits, and other media works and is designated as a National Historic Landmark. Its design has influenced that of other houses and Mies's later work.

The Farnsworth House is located in Kendall County near Plano, Illinois, United States, about 58 miles (93 km) southwest of Chicago. The house is situated on a floodplain along the north bank of the Fox River and is surrounded by trees on three sides. Fox River Drive runs west of the house, behind the trees, while a grassy meadow slopes slightly upward to the north. To keep the house cool during the summer, the southern facade was shaded by a black maple, which was removed in 2013. The original owner, Edith Farnsworth, hired the architect Alfred Caldwell to arrange orchards and gardens about the property. The house was originally not built with any vehicular access. A two-car garage was later built to the north, and the second owner, Peter Palumbo, hired the landscape architect Lanning Roper to build a serpentine gravel driveway. Roper and Palumbo planted 350 trees on the estate over several years, and Roper also designed an English–style meadow and daffodil gardens surrounding the house.

The house is part of an estate that is variously cited as covering 58 acres (23 ha) or 62 acres (25 ha). The estate includes the main house, a tennis court, swimming pool, and outbuildings such as a boathouse and fieldhouse. Under Palumbo's ownership, the estate had sculptures by Harry Bertoia, Alexander Calder, Anthony Caro, Andy Goldsworthy, Ellsworth Kelly, Henry Moore, Claes Oldenburg, and Richard Serra. Palumbo also displayed objects such as British telephone boxes and a piece of the Berlin Wall. When the house opened as a museum in the 21st century, the estate had 2.5 miles (4.0 km) of trails.

There is a visitor center about 0.5 miles (0.80 km) east of the main house. Built by Palumbo, one of the house's past owners, the visitor center was originally a prefabricated building with a metal facade. In the 2000s, the visitor center's facade was covered in wood. The Barnsworth Gallery, which contains temporary exhibition space and storage areas for the Farnsworth House's wardrobe, is next to the visitor center. Built by Illinois Institute of Technology students, the Barnsworth Gallery has a circular floor plan and includes construction materials salvaged from other construction projects in Illinois.

The original owner was Edith Farnsworth, a kidney doctor from Chicago, who recalled being lonely and overburdened with work despite her successful career. She was a single, middle-aged woman at a time when relatively few American women lived such a lifestyle. The house's architect, Ludwig Mies van der Rohe, had been refining his designs for decades before the Farnsworth House commission and had moved to the U.S. in 1938. He had evolved from using traditional architectural styles in the 1900s to using more modernist styles by the 1930s, and he had built several structures that combined glass facades and more traditional courtyards. For several years, Mies had wanted to build living rooms with glass walls, leading historians to suggest that Mies may have designed the Farnsworth House primarily to further his own design objectives.