What structure was built by the communists in 1961 to separate east Berlin from West Berlin and then torn down in 1989?

The structure built by the communists in 1961 to separate East Berlin from West Berlin was the Berlin Wall. It served as a physical barrier to prevent East Germans from fleeing to the West, symbolizing the division between the communist East and the democratic West during the Cold War. The Berlin Wall was torn down in 1989, marking a significant moment in history that contributed to the fall of communism in Eastern Europe.