The original Enterprise model from Star Trek is undergoing renovations before being moved to main entrance of the Smithsonian's Air and Space Museum. You can read an interview with the conservator leading the preservation project, Dr. Margaret Weitekamp, at Trek Core.
Clarification, the model is not currently at the downtown DC location of the Air and Space Museum at 401 Independence but out in Chantilly, VA at the Udvar-Hazy extension of the museum. If you want to see it in person before restoration is complete, there will be an event in January.
ETA: After restoration it will go back to DC