Berlin Wall

The ' (German: Berliner Mauer') was a concrete barrier that physically divided and  from each other. It was constructed in 1961 and was destroyed in 1989, though some smaller segments of it still remain. Despite its deep political origins, it has appeared a few times within Super Mario media.

Mario is Missing!
The Berlin Wall is one of the landmarks of Berlin visited by Luigi in the DOS version of Mario is Missing!. In a raid on the city, Bowser sends his Koopa Troopas to steal one brick from the Berlin Wall, which forces it to close down. Luigi must find and return the brick so that the Berlin Wall can reopen to tourists. However, in order to prove the brick's authenticity, he must answer two trivia questions with the correct answers, written here in bold:
 * When did the East Germans begin to build the Wall?
 * 1961
 * 1700s
 * 1989
 * For what reason did they build it?
 * To keep East and West Germany separate
 * They were chilly during the Cold War
 * To hang pictures

Mario's Time Machine
In Mario's Time Machine, Bowser travels back in time to 1989 and steals a single Sledgehammer from the site, which is apparently enough to halt its destruction. The Berlin Wall then becomes filled with Bodyslam Koopas and Koopa Troopas. Mario later travels back in time to the Berlin Wall himself to return the Sledgehammer while the Koopas attempt to stop him. He eventually reaches a guardpost (at the far-right of the screen) and drops off the Sledgehammer. Mario then travels back in time to the present as a news article congratulates Mario for helping topple the Berlin Wall.

Mario Kart series
The Berlin Wall appears in Berlin Byways in Mario Kart Tour. It receives most of its focus in the first layout of Berlin Byways, where Whomps stand in holes in the wall and attempt to crush racers.

Berlin Byways returns in Mario Kart 8 Deluxe as part of the third wave of the Booster Course Pass DLC; as such, the Berlin Wall and its Whomps are still present. Players drive past it during the final lap of the course.

Muro di Berlino