Two Skylab modules were built. The first launched in 1973, was occupied as a science laboratory for 171 of its 2,249 days in orbit, and re-entered Earth’s atmosphere in 1979. Read more about Skylab HERE and HERE.
The second, Skylab B, is on display at the National Air and Space Museum in Washington, DC, where visitors can walk through its living and working quarters. Here’s the view (times 5):