On December 18, 1965, the Gemini VII spacecraft, crewed by Frank Borman and James Lovell, splashed down in the Atlantic Ocean after 13 days, 18 hours, and 35 minutes in space, completing 206 orbits around the Earth. The main purpose of the mission was to demonstrate that spacecraft systems and human crew could fly in space for longer than planned lunar missions without problems. Gemini VII set a spaceflight endurance record which would stand for five years until broken by the 28 day Skylab 2 mission in 1973. Here is a NASA documentary film, “Proud Conquest” about Gemini VII and the concurrent flight of Gemini VI-A, which performed the first space rendezvous when it joined Gemini VII in orbit.
When Gemini VII set an endurance record, the key word was “endure”. The crew spent two weeks in a space described as comparable to the front seat of a Volkswagen bug. The Smithsonian, which displays the spacecraft, has prepared a 360° panorama image that lets you “look around” as if you were in the spacecraft. Imagine spending two weeks there, without even being able to open the hatch and throw out trash or excreta. And there wasn’t a shower in the back.