Despite all the efforts made by the East German government to keep their people out of West Berlin, an estimated 5,000 people were able to cross the Wall. Some disguised themselves and used other ruses, others dug tunnels, several even flew over in homemade balloons. Several successful devices are on display at the Checkpoint Charlie museum, including a Volkswagen equipped with a secret compartment -- which smuggled several people out of East Berlin into the West.