What was the Berlin Wall?

"In 1961, overnight a concrete border went up, dividing the city of Berlin into two parts--East and West. The story of the Berlin Wall holds up a mirror to post-WWII politics and the Cold War Era when the United States and the USSR were enemies, always on the verge of war. The wall meant that no one from Communist East Berlin could travel to West Berlin, a free, democratic area. Of course that didn't stop thousands from trying to breech the wall - more than one hundred of them dying in the attempt. . . . Medina explains the spy-vs-spy politics of the time as well as what has happened since the removal of one of the most divisive landmarks in modern history"--Provided by publisher.