Up Close With the Space Shuttle Enterprise.

From: Up close with the Enterprise shuttle at the Intrepid Museum

This shuttle, OV-101, never made it to orbit but was used in-atmosphere for testing purposes. At one time it was considered for a retrofit — adding engines and a heatshield so that it would be able to make it to space and back — but NASA opted to build Challenger instead. So while it’s not exactly the crown jewel of US space flight history it’s still an impressive piece of work and something that it is extremely inspiring to be in the presence of.