Artist’s concept paintings depicting the American and Soviet spacecrafts in Earth orbit during the July 1975 Apollo-Soyuz Test Project mission.

The first docking of spacecraft from two different nations happened on July 17, 1975. The American and Soviet ASTP crewmen visited each other’s spacecraft while Apollo and Soyuz were docked for two days. The docking system on the Docking Module and the docking system on the Soyuz Orbital Module are designed to interface with each other. 

Artists: Paul Fjeld (1-5), Davis Meltzer (6-8) and Robert McCall (9).

Source: NASA Human Spaceflight gallery