Power? Strength? Control?

Just how strong truly are we? I have heard that we "are a great nation," and that "the foundation of our biggest buildings" can fall, but our resolve cannot. However I truly know that like each great nation, for example Rome, can fall to simple enemies. The things that matter right now is that "our country is strong." The longer we last is important, but just how strong are we? Each nation has had its problems, and can we see ours....?