Bus
Peter Pan Bus Lines is a 5 minute drive from downtown.
Railways
AMTRAK railroad station is a 5 minute drive from downtown.
Not so great for the kids. Little boys will enjoy the "army" aspect, but the kids didn't enjoy looking. There are no activities and nothing to participate in. So unless you kids love guns, military and history, this isn't the best place for some fun. On the other hand it is an excellent place to learn about history in a more dynamic way than reading a book about it.
National Armory, site chosen by General Washinton. Museum features huge firearm colletion, interactive exhibits, introductory film, and bookstore.