The Stanford Torus
The is called the Stanford Torus, and it was introduced in 1975 as a proposed design for a space habitat. The Stanford Torus got its name from the proposal being discussed at Stanford University, and the design including a torus – a doughnut shaped ring. mmm Space donut
The ring rotates once per minute creating artificial gravity from the centrifugal force. Stanford Torus was designed to house 10,000 to 40,000 permanent residents. Sunlight was provide to the interior via solar mirrors.
The torus would require nearly 10 million tons of mass! Construction would have to use materials extracted from the moon or asteroids. Luna soil would be used as a radiation shield.
The Bernal Sphere
This space habitat was first proposed in 1929 by John Desmond Bernal. It was described as a hollow non-rotating spherical shell with a 10 mile diameter, filler with air. It was to hold 20,000 to 30,000 people.