Green Monster

The left field wall at Fenway Park, home of the Boston Red Sox, is famously called the Green Monster. It stands 37 feet tall and is 310 feet from home plate along the left-field foul line, a distance that often appeals to right-handed batters.

The wall has been part of the ballpark since its original construction in 1912, running along the north side facing Lansdowne Street. Originally made of wood, it was covered with tin and concrete in 1934, then hard plastic in 1976. A manual scoreboard has been set into the wall in some form since at least 1914. Before being painted green in 1947, the wall was covered with advertisements. The nickname "Green Monster" appeared in print by November 1956, though for many years it was simply called "The Wall," a name still used today.

Among current Major League Baseball fields, the Green Monster is the highest wall, and it is the second highest among all professional baseball fields, including the minors. In 2007, it was surpassed by "The Arch Nemesis," the left field wall of WellSpan Park in York, Pennsylvania, which is about six inches taller. The wall’s height was temporarily beaten in 2001 and 2002 by a 40-foot black wall in center field at Riverfront Stadium in Cincinnati, called the "Black Monster," erected during construction of Great American Ball Park. That wall was demolished with the stadium in 2002, returning the record to Fenway.

High fences in baseball have often been used to block outside views of the field, particularly where bleacher seating is low or absent, and to reduce cheap home runs. Fenway’s wall serves both purposes. Past ballparks with similarly high fences include Baker Bowl, Washington Park, Ebbets Field, League Park, Griffith Stadium, Shibe Park, and the Los Angeles Memorial Coliseum. Fenway is the last major-league ballpark with an exceptionally high wall still in use; newer parks sometimes build high walls for novelty rather than necessity.

The Red Sox mascot, Wally the Green Monster, honors the wall. In May 2025, the team announced a City Connect jersey inspired by the Green Monster, featuring a solid green color and lettering matching the font on the wall.

The wall is 37 feet tall and 231 feet wide, giving it a surface area of 8,585.5 square feet. It is marked as 310 feet from home plate at the left-field foul line, though until May 1995 it was listed as 315 feet. The metric distance was not adjusted from 96 meters to 94.5 meters until 1998. Near the flagpole in center field, the wall is marked as 379 feet deep, with a vertical yellow line indicating the rightmost part of the wall in play. A ball hitting the wall to the right of that line is a home run. In contrast, the right-field wall is less than 6 feet tall, marked as 302 feet from home plate at the Pesky Pole, but it angles back to 380 feet at the bullpens, making right field significantly larger than left.

The Green Monster prevents many line drives from becoming home runs, often turning them into doubles—a result called a "wallball double." The major-league record for doubles in a season was set by Red Sox player Earl Webb with 67 in 1931, though only 33 were hit at Fenway. No player has reached 60 doubles in a season since 1936. Experienced left fielders learn to play caroms off the wall to throw out runners or hold batters to singles.

The wall’s placement creates a shallow left field, so many long fly balls that would be caught elsewhere bounce off for hits. Hall of Famer George Brett, who occasionally played left field, called playing left at Fenway one of his favorite career moments. While the wall stops line-drive homers, it also allows some high, shallow fly balls to become home runs, as seen with Bucky Dent’s 1978 tie-breaker homer. Don Baylor, a Red Sox player from 1985 to 1987, noted that high fly balls that are outs in most parks can be home runs here.