Aberdeen Proving Ground Ordnance Museum
Located on post at the Aberdeen Proving Ground, this is my favorite place to visit when in the Aberdeen area. The collection of tanks, artillery, small arms, etc is absolutely awesome. (I don't say that lightly!) This is on my list of must see places, especially for ex-military types. Even my wife found in fascinating!!!!
The museum is operated by the U.S. Army Ordnance Museum Foundation, Inc.
Directions for accessing the museum are on the first page.
You retired military types might want to consider hitting the commissary or PX while you're there.
For what it's worth - The last time I visited APG I was hanging out for a week or so around Lancaster, PA, doing the Pa. Dutch County thing. It was about a 45 mile drive to Aberdeen. Makes a good, and easy, day trip.