Aberdeen Proving Grounds museum
The great thing about this museum in VA is that the Tanks and artillery all have a roof over them. This place is so large that they could take in even more!
I have heard that the museum at Aberdeen has the tanks out in the weather year round and many have some real serious rust problems. Hopefully they will eventually get some under shelter, especially the older WW1 era tanks and artillery that have already endured too many winters.