When Fenway Park was built in 1912, the 25 foot tall left field wall was covered with advertisements. At the front of the wall was a 10 foot incline of dirt. This mound proved difficult for most players to field on, except for Duffy Lewis. Lewis became so legendary for his skill on the incline that it was referred to as “Duffy’s Cliff”. In 1917, Lewis left the Red Sox to serve in World War I and opted to play for the Yankees when he returned in 1919. In 1934 Sox owner Tom Yawkey had the mound flattened to field level.
1947 saw the advertisements painted over, the wall painted green and raised to a height of 37 feet. The green monster as we know it was born. The most recent additions to the Monster came in 2003 with the creation of the Green Monster Seats, and in 2005 with the additon of the Nation’s Nest. Both of these modifications were extremely well done, and most fans comment that they look like they were always there.