KANSAS CITY, Mo. (AP) — They sit across a wide table from each other in a glass-walled conference room, the two men with graying hair trading barbs just as breezily as they trade praise.

"We're sort of an 'Odd Couple' kind of thing," Joe Spear muses during a break in the banter, scratching at his goatee. "But we do think surprisingly alike."

"Scary thought," replies Earl Santee, leaning back in his chair.

Over nearly three decades, the two men have built Kansas City-based Populous from an offshoot of design firm HOK into the pre-eminent sports architecture company in the country. They've designed everything from Olympic buildings to minor league ballparks, in the process doing as much to shape the fan experience as any athlete or owner.

Now the best friends are working together on what could be their most ambitious undertaking yet: SunTrust Park in Atlanta, the centerpiece of a mixed-use development that will include upscale residences, hotels and retail space.

In many ways, it could be the future of ballpark development.

Sure, other stadiums have served as the impetus for urban renewal. Some have even had hotels and other amenities built alongside them. But the project for the Braves is the first time that a major sports venue and surrounding community have been designed in concert.

"We examined others — other companies, other architects. But we just had a comfort level with Joe and Earl," said Braves president John Schuerholz, who first worked with the men when he was with the Kansas City Royals in the 1970s. "They spoke the same language, they understood what we were asking for and they understood the challenges they would face."

No challenge could be too daunting for this odd couple.

Their forte is stadiums for Major League Baseball, a sport that lends itself to creativity more than perhaps any other. With the exception of the base paths (90 feet apart) and pitcher's mound (60 feet, 6 inches from home), the only limiting factor is the imagination.

Want to add an outfield berm? Go ahead. Build a wall that zigs when it ought to zag? Sure. Position the entire stadium on the edge of the ocean? Go for it.

Spear and Santee have combined to design 13 of the last 14 parks to open, including PNC Park in Pittsburgh and AT&T Park in San Francisco, widely considered two of the game's best. They have had their hand in the design or major renovations of 20 current ballparks, and 24 of the 30 clubs have collaborated with their firm in some fashion over the years.

While they have occasionally shared feedback and ideas over the years, Spear and Santee usually work separately. Populous often has several projects going at once, making it impossible for them to spend time on the same stadium. For another, the clash of concepts can sometimes lead to conflict, even among the best of friends.

But they've put that aside for the project in Atlanta, given its unique nature. And the result is the best of both worlds: Spear and his brilliance at envisioning a park's overall look and feel, and Santee with his strengths in creating event spaces and fan amenities.

"There must be a brainstorming office where they go in there and they turn on the think-o-meter or think-o-tron or whatever it is and it spits out something incredible," said John McHale, who chose Populous to build Coors Field in Denver and Comerica Park in Detroit, and is now vice president of administration for Major League Baseball.

It was Spear who first dreamed up the concept of retro ballparks in the early 1990s, back when baseball was played primarily in concrete doughnuts. With the B&O Warehouse serving as his backdrop, he fashioned Oriole Park at Camden Yards, a groundbreaking achievement that not only has stood the test of time but has influenced nearly every stadium to follow.

Yet while new designs tend to borrow from existing ones, Spear and Santee are careful each ballpark is its own entity. Their cues come from each city, its franchise and its fans.

At the new Busch Stadium in St. Louis, Santee made sure the Gateway Arch would be visible beyond the outfield wall. At the new Yankee Stadium, a sense of history and austerity was created. Over in Queens, an homage to Ebbets Field in the guise of the Mets' Citi Field.

"We don't have any preconceived ideas," Santee said. "We didn't on Atlanta or anywhere else. We are clearly defining all the future experiences, but they are uniquely designed."

They are subject to change, too. Even elements of the most timeless stadiums become outdated (just ask folks living near Wrigley Field). So, Spear and Santee often revisit their own projects and offer tweaks, such as the new open-air party decks at Coors Field.

That's not to say they don't try to create everlasting stadiums. In some ways, each new ballpark is like a child, and asking them to pick a favorite is a waste of time.

"We never answer that question," Spear said.

They do have what they call "favorite moments." Bits and pieces done right.

One is the majestic view of the Pittsburgh skyline from inside PNC Park. Another is the smooth waters of McCovey Cove just outside AT&T Park in San Francisco. And the soaring atrium as one passes from Union Station into Minute Maid Park in Houston.

"I don't know why," Santee said, "but those are the things I think about."

There is hardly time for Spear and Santee to dwell on the past. Not with the centerpiece of a $1 billion development awaiting final touches in Atlanta. SunTrust Park is already under construction, and the Braves are scheduled to move in for the 2017 season.

"It really looks like this will be the apotheosis of the ballpark development boom — of the past 30 years," said McHale, the MLB executive. "This is going to be a blockbuster project."

No surprise coming from two architects who have been at the forefront for decades.