Aberdeen, Maryland city that built the American army and American baseball epicenter is located 48 kilometers from Baltimore. The city has been the testing ground for U.S. Army since 1917. Visitors can access the Military Museum United States Army Ordnance Museum with a one-day pass, which will find a collection of historic artillery and tanks from around the world. But Aberdeen is also home of the legendary Ripken family, whose existence has been immortalized with pride in the ballpark, museum and playgrounds.