rules, which requires all outfield walls to be padded, Wrigley Field was grandfathered into the rules, meaning it is the only stadium in the league without padded walls because of the ivy. In 2004, the ivy was specifically included in Wrigley Field's Landmark Designation by the Chicago City Council. Although the ivy appears to "pad" the bricks, it is of little practical use in this regard. There have been occasions of fielders being injured when slamming into the wall while pursuing a fly ball. Under the ground rules of Wrigley Field, if a baseball gets into the ivy and gets stuck, the batter is awarded a ground rule double. Outfielders often raise their arms up when the ball goes into the ivy, signaling to an umpire to go out and rule on the play. However, if the ball becomes dislodged or the fielder reaches into the vines to try and retrieve it, it is considered in play and the runners can advance. Dimensions The distances from home plate to various points in the outfield have remained essentially unchanged since the bleachers were remodeled during the 1937 season. They were originally marked by wooden numbers cut from plywood, painted white, and placed in gaps where the ivy was not allowed to grow. Since the early 1980s, the numbers have been painted directly on the bricks, in yellow. Although the power-alley dimensions are relatively cozy, the foul lines are currently the deepest in the major leagues. It is to the notch in the wall just beyond the left field foul pole. The point where the bleacher wall begins to curve inward in left-center field, one of the two "wells", is an unmarked . The front part of the left-center "well" is the closest point in the outfield, about . The marked left-center field distance is . It is closer to true center field than its right-center counterpart is. True center field is unmarked and is about . The center field marker, which is to the right of true center field and in the middle of the quarter-circle defining the center field area, is and is the deepest point in the outfield. Right-center field is , the notch of the right-center "well" is an unmarked , and the right field foul line is . As of 2004, the backstop is listed in media sources as behind home plate. Although that distance is standard,