In the very early morning hours of Friday, April 14, 1911, a fire of uncertain origin swept through the stadium's horseshoe-shaped grandstand, consuming wood and leaving only steel uprights in place. The gaps between some sections of the stands saved a good portion of the outfield seating and the clubhouse from destruction. Giants owner John T. Brush decided to rebuild the Polo Grounds with concrete and steel, renting Hilltop Park from the Highlanders during reconstruction.
Progress was sufficient to allow the stadium to reopen just three months later, June 28, 1911, the date some baseball guides date the structure. As configured, it was the ninth concrete-and-steel stadium in the Majors and fourth in the National League. Unfinished seating areas were rebuilt during the season while the games went on. The new structure stretched in roughly the same semicircle from the left field corner around home plate to the right field corner as prior but was extended into deep right-center field. The surviving wooden bleachers were retained basically as is, with gaps remaining on each side between the new fireproof construction.
This version of the ballpark had its share of quirks. The "unofficial" distances (never marked on the wall) down the left and right field lines were 279 and 258 feet (85 and 79 m) respectively, but there was a 21-foot (6.4 m) overhang in left field, which often intercepted fly balls which would otherwise have been catchable and turned them into home runs. Contrasting with the short distances down the lines were the 450 distances in deepest left and right center (the gaps), with the base of the straightaway centerfield clubhouse standing 483 feet distant from home plate, up a 58-foot runway from the grandstand corners on either side of the clubhouse, which were themselves 425 feet (130 m) from home plate. The famous photo of The catch made by Willie Mays in the 1954 World Series against Vic Wertz of the Cleveland Indians occurred immediately in front of the "batter's eye", a metal screen atop the grandstand wall directly to the right of the centerfield runway. It would have been a home run in several other ballparks of the time as well as in most of today's modern ballparks. The bullpens were actually in play, in the left and right center field gaps. The outfield sloped downward from the infield, and people in the dugouts often could only see the top half of the outfielders.
The New York Yankees sublet the Polo Grounds from the Giants during 1913–1922 after their lease on Hilltop Park expired. After the 1922 season, the Yankees built Yankee Stadium directly across the Harlem River from the Polo Grounds, which spurred the Giants to expand their park to reach a comparable seating capacity to stay competitive. However, since nearly all the new seating was in the outfield, Yankee Stadium still had more desirable seats than did the Polo Grounds for watching baseball. However, the Polo Grounds became better suited for football due to the new seating placement.
The Giants' first night game at the stadium was played on May 24, 1940.
The Polo Grounds was the site of one of the most iconic moments in baseball history - the historic "Shot Heard 'Round the World" walk-off home run on October 3, 1951 that decided the hard-fought National League pennant playoff series between the Giants and their cross-town rivals, the Brooklyn Dodgers.