Gemini 4 Hatch

Gemini 4 itself is displayed at the National Air & Space Museum, but its command pilot hatch was displayed at the Cradle of Aviation for some time. The Smithsonian has since recalled the hatch in preparation of renovating its Milestones of Flight Gallery (the gallery in which Gemini 4 is displayed) and in return gave the Cradle the hatch of an unmanned Gemini spacecraft.

This hatch is NASM catalog #A19680035000