Salyut 3
Salyut 3 was a space station in the Soviet Union's Almaz program. It was also known as OTS-2 and Almaz 2. The size and shape were similar to Salyut 1, but the rest of the design was very different. This was because it was part of the Almaz program instead of the Salyut program. It was only named Salyut 3 to hide its real purpose. In reality it was a military station for spying on other countries. Most details of it were not known until after the Cold War was over.