structures. For example, his Carceri d'invenzione or Imaginary Prisons from 1745 depicts labyrinthine monumental spaces and mysterious machines. Visionary architecture of the 18th century centered around projects of immense size that "defied both man's comprehension and his building techniques." Claude Nicolas Ledoux is known for his utopian designs, including the City of Chaux around the Royal Saltworks at Arc-et-Senans. Ledoux developed an entire master plan for Chaux, along with architectural drawings, elevations, and sections of various individual buildings. Ledoux also designed a tube-shaped house for the director of the waterworks by the Loire river, . Jean-Jacques Lequeu is one of the more eccentric and shocking of the early visionary architects. After the French Revolution ended his chance to become a palace architect, he worked as a civil servant, cartographer, surveyor, and draftsman. However, he spent most of his time preparing an unpublished treatise, Architecture Civile, which features ornaments, fragments of architectural drawings, and a series of fanciful architectural designs. These designs typically show an elevation or section of a building but rarely an entire design. One of his visionary designs was a stable shaped like a cow. Étienne-Louis Boullée was an 18th-century visionary neo-classical architect. He was also an influential architectural theorist because he taught at the École Nationale des Ponts et Chaussées and elsewhere for fifty years. Later in his career, Boullée's designs showed an abstraction of geometric forms, removing all unnecessary ornamentation and inflating geometric shapes to a huge scale. In his La Théorie Des Corps, he discussed the properties of geometric forms such as the cube, cylinder, pyramid, and sphere and their effect on the senses. He believed the sphere was the "ideal form". The early motion picture industry impacted architecture, especially the films Metropolis and Just Imagine, with their elaborate, imaginative, and futuristic architectural sets. Hugh Ferriss is one visionary architect who was influenced by Hollywood. He included sixty of his drawings in his 1929 book The Metropolis of Tomorrow. Ferriss divided his book into three sections: Cities of Today, Projected Trends, and An Imaginary Metropolis. In the third section, he predicts a city with tall, looming skyscrapers and bridge dwellings that were impossible to build at the time. In the 20th century, visionary architects surfaced in repressed societies where young architects had little hope of realizing their designs. Early 20th-century Visionary architecture is divided into three main movements: German expressionism, Italian futurism, and Russian constructivism.