Project Gemini from NASA was created to test technologies and techniques that will be later put in use in the Apollo program, the Gemini spacecraft was bigger and more advanced than the Mercury and could hold two man. When designing the Gemini project these were the main goals: Precision atmospheric reentry. Extra Vehicular Activity ( EVA) or spacewalking. Fuel cells to generate electricity and water. Perfect rendezvous and docking between two spacecraft. Techniques for propelling and maneuvering two docked spacecraft. Long term human spaceflight.
The Gemini spacecraft was designed by a team of NASA engineers led by Jim Chamberlin and was built by McDonnell Aircraft in St Louis, the Gemini flights helped NASA learn how to work and live in space, paving the way for the Apollo human landing on the Moon. Here are some breathtaking photos of that project