The Presidential Limousine, known officially as "Cadillac One" and called "the Beast" by the Secret Service, is a remarkable machine. The president's car is capable of transporting and protecting him, letting him work undisturbed, and if necessary, unleashing nuclear hell. President Obama's car is a unique vehicle built around a Cadillac DTS that almost everyone has seen, but almost nobody knows anything about. And that's on purpose - the details of its protection and weapons are closely guarded secrets.