Which wall divided a European city until 1989?

The Berlin Wall split the city from 1961 until 1989. After the war Berlin had been divided into occupation sectors, leaving West Berlin as an island of Western territory deep inside communist East Germany. That made it an escape hatch: East Germans could reach the West simply by crossing to the other half of the city, and millions left, many of them young and skilled, which the East German state could not sustain. The wall was thrown up almost overnight in August 1961 to close that route, and it grew into a fortified strip with watchtowers, tripwires and a cleared death strip. It came down not through negotiation but through confusion, when a mishandled announcement about relaxed travel rules on the evening of 9 November 1989 sent crowds to the checkpoints and overwhelmed guards who had no orders to shoot. German reunification followed within a year.

Checkpoint Charlie was the crossing point reserved for Allied personnel and foreigners.