The company changing the face of baseball by Chris Matthews @FortuneMagazine 12:21 PM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons Last year was one for the baseball record books, just not in a good way. If it hadn’t been for the Kansas City Royals forcing a dramatic game seven in the World Series, the 2014 Fall Classic would have had the lowest TV ratings ever. It wasn’t a fluke. For decades nationwide baseball broadcasts have seen their numbers steadily decline. And yet people ar still turning up at the ballpark: 73.7 million of them last year, up from 50 million 20 years ago. In the first two weeks of the 2015 season, 3 million people attended games, the highest turnout in baseball history. The surge in attendance has coincided with the remarkable rise of one architecture firm: Kansas City–based Populous. After the completion of the new Atlanta Braves stadium in 2017, it will have designed 20 of the 30 current Major League ballparks, orchestrated the renovations of five others, and changed the way we watch—and pay for—baseball. Joe Spear founded the firm in 1983 as the sports division of the design company HOK (it spun off in 2008 as Populous). The company surged to national prominence in 1992 with the construction of Oriole Park at Baltimore’s Camden Yards. The design incorporated a B&O warehouse building into the stadium design, allowing the original brick structure to serve as the backdrop behind right field. Seemingly overnight, a “retro” craze in stadium design was born. The ballpark also introduced new premium dining options, club seating, and “experiential add-ons,” like games for kids and on-site bars. By shrinking foul territory, it allowed the team to place seats closer to the action and charge more for tickets. “Camden Yards was a game changer,” says Robert Boland, a sports business consultant and professor at New York University. “It not only changed the design of the ballpark, but it also changed the revenue capability of a ballpark. Everyone had to have it.” Populous’s ensuing building spree expanded the definition of a sports venue, even after the retro trend faded. Marlins Park, which opened in Miami in 2012, features palm trees, an aquarium behind home plate, and a nightclub with scantily clad dancers and a swimming pool. The new Populous-designed ballpark in Atlanta, which broke ground this year, will be part of a broader mixed-use development, including residential apartments, office space, a hotel, and a concert venue with a capacity of 4,500. Populous’s next project is a stadium complex with offices, an Omni hotel, and apartments built in.Courtesy of Populous “More and more professional sports teams are getting into the real estate business,” says Braves marketing chief Derek Schiller. “It’s so important to control what happens outside the park too.” The arrangements, which allow teams to cash in on games’ traffic, are likely to become more popular as stadiums broaden the scope of the American summer ritual, as well as its appeal. Baseball viewership may be down, but the national pastime is alive and well. This story is from the June 1, 2015 issue of Fortune magazine.