(Business 2.0) – From the game-day blimp, Houston's new Reliant Stadium--home of the Houston Texans, the National Football League's newest franchise--looks positively dangerous. With its retractable roof agape, it seems ready to bite the top off the nearby Astrodome. Everything inside 69,500-seat Reliant is Texas-size as well: It has the biggest scoreboard in the NFL, flat-screen TVs and leather couches for club-level seatholders, and 666 concession-stand cash registers--all collected in a space 900,000 square feet larger than the Astrodome, the stadium once hailed as "the eighth wonder of the world."

What's most impressive about Reliant, however, is that despite its epic scale, watching an NFL game there can seem as cozy as attending a high school contest. The cheapest 50-yard-line seats are just 135 feet from the gridiron--95 feet closer than those at the Astrodome.

This feeling of intimacy amid vastness is one of the trademarks of Kansas City-based HOK Sport, the architecture firm that during the past two decades has single-handedly revolutionized stadium design and marketing. No fewer than 12 of the last 17 new NFL stadiums and 10 of the last 16 new Major League Baseball parks were built to HOK blueprints. Much has been written about the company's artful use of nostalgic design cues. But the real breakthrough was its realization--long before the idea dawned on competitors, team owners, or big-city officials--that sporting events aren't really about the game being played down on the field. They're mainly about the business taking place around it.

If you've ever taken in a game at one of the concrete mega-bowls that opened in the 1960s and 1970s--Veterans Stadium in Philadelphia, say, or Candlestick Park in San Francisco--you probably noticed that it had all the charm of a dirty ashtray. In the early '80s, the same thought struck Ron Labinski and three younger architects, Joe Spear, Chris Carver, and Dennis Wellner, at the Kansas City-based design firm HNTB. At the time, the boom in dual-use football and baseball stadiums had crested and the grumbling had set in. Fans hated the Frankenparks' lousy views, and teams were frustrated by inadequate opportunities to make money from concessions and premium seating.

So Labinski and the others made a list of 17 stadiums that would soon have to be replaced and took it to Jerry Sincoff, vice chairman of Hellmuth Obata & Kassabaum, the architecture firm behind Houston's Galleria and Saudi Arabia's King Saud University. Why, they asked, shouldn't the firm go after that impending business with a sports-only design division? Sincoff agreed and put Labinski and his team in charge.

Several important innovations evolved during construction of HOK Sport's first major project, Miami's Joe Robbie Stadium (since renamed Pro Player Stadium) in 1985. Robbie, the late Miami Dolphins owner, had approved HOK's blueprint, but he still needed funding to finish the $115 million job. Labinski suggested creating a 10,000-capacity high-end seating area, with its own entrances, better concessions, and swankier seats, and selling 10-year leases on those seats. Robbie used the guaranteed leases as collateral to secure loans for the $90 million he needed to finish construction. So-called club-level seats have been a key moneymaker in every HOK venue since.

The firm then began making changes in stadium design. The breakthrough was Baltimore's Camden Yards, whose rectangular layout and red-brick facade conjured up nostalgic memories of the urban ballparks of the '20s and '30s. With a warehouse looming over the right-field wall, the stadium seemed attached at the hip to the city itself. Later HOK design elements help spectators feel like part of the action. For example, the bull pens at San Francisco's Pacific Bell Park, which opened in 2000, sit directly in front of the seats along the first-and third-base lines. Apart from the players themselves, fans in those seats are the first to know when a manager is getting worried about his starting pitcher. The feeling of involvement, it turns out, is a marketable commodity: At Reliant, end-zone ticketholders pay $44.50 a head to be part of a designated area for rowdies--despite having the worst view in the entire stadium.

Such fieldside attractions might win kudos from the fans, but it's the layout away from the game that clinches the deal with owners. Beginning with the Miami stadium, HOK has constantly increased the size of non-seating areas to squeeze in more and more concessions and luxury perks. (Reliant features one concession cash register for every 125 spectators, the highest concentration in the NFL.) While an old football stadium might fit 65,000 people into 1 million square feet, HOK parks typically offer 700,000 more square feet for the same number of fans. That means more room for moneymakers such as the "Park at the Park" planned for the new San Diego Padres stadium, set to open in 2004. Situated beyond the center-field wall, it will be enveloped by retail shops so fans can duck into Banana Republic if a pitchers' duel grows dull. Earl Santee, who heads HOK Sport's baseball practice, explains the formula this way: "The event is the background. The foreground is all these other activities. It's 'I need to buy a sweater' or 'There's a beer garden.'"

How does this translate to the bottom line? In San Francisco, the Giants averaged less than 2 million in annual attendance at 60,000-seat Candlestick Park and lost $97 million between 1995 and 1999. In its first three years at 40,000-seat Pac Bell, the team has averaged more than 3 million spectators. Revenue has doubled, and the club managed a small profit for the 2002 season, even after making its annual $20 million payment to the investors who fronted $140 million for the park. Not bad, considering that most team owners claim they can't make a dime.

Results like that make HOK stadiums an easy sell, but the company takes no chances, beginning the sales process long before a stadium wears out. "If we're doing our job right, we've already been talking to [team owners] for 15 years" before they build the stadium, says company spokeswoman Carrie Plummer. By striking first, the firm can preempt rivals like HNTB and Ellerbe Becket. Many teams, including the Texans, hired HOK without soliciting other bids. Santee claims he hasn't had to compete for a job in seven years.

Some architecture experts deride HOK buildings as boring and formulaic, but users point out that stadiums are commercial venues, not works of art. "I love Frank Gehry's buildings," says Steve Patterson, Texans vice president for development. "They're dramatic and exciting, but I've got to build something that accommodates 70,000 people buying beers and hot dogs and parking, and I've got to be able to clean it and staff it." Non-HOK venues, he says, can cost twice as much to staff per spectator.

About the only problem for which HOK has so far failed to find an architectural solution is what takes place down on the field. At Reliant, tickets are sold out, fans are happy, and concessions pull in $1.4 million during every home game. But the Texans? They're well on their way to one of the worst records in the league. --IAN MOUNT