The answer was the All-Star Game, first played in 1933. It's become an annual event, next scheduled for July in Arizona, and one emulated by other sports.
Now there's a new question: "What if you could watch the best players in baseball history on the same field at the same time?"
The answer: MLB Network's brand-new "All In One Place" 45-second spot -- which premiered Monday and is now available for close inspection on MLB.com. It's a technical marvel that was seven months in the making, narrated by Bob Costas -- a blend of black-and-white and color footage, with past and present greats mingling on the famous Studio 42 field.
Fittingly, the studio's namesake, Jackie Robinson, opens the spot by climbing up the dugout steps and racing onto the field past Tony Gwynn and Ken Griffey Jr.
Other pre-integration players hang together with their post-1947 counterparts: Babe Ruth throws a baseball to Willie Mays, while Ty Cobb and Frank Robinson share a private moment on the field.
"Hopefully fans will take to it and get a kick out of this," MLB Network CEO Tony Petitti said. "We thought about the fact we had all these great guests come into Studio 42, and it got us thinking it would be fun to put players from different generations on the same field in different ways."
How did they do this?
"Seven months ago, Tony [Petitti] said, 'You're going to kill me, but I want to create some sort of "Field of Dreams" in Studio 42 downstairs,'" recalls Chris Mallory, vice president of creative services at MLB Network. "My reaction was, 'OK, but you're not getting it on Friday.' Now he has it, after a lot of criticism and going back and forth.
"It really came about from first putting together an A-list of players, and having a researcher go through many, many, many hours of old games. It was frankly footage that networks wouldn't necessarily care about: Guys standing around in old All-Star Games and stuff. ... We went through 1,000 hours of footage."
There were "a few good accidents," such as "the Derek moment" -- an obscure clip of Yankees shortstop Derek Jeter from 2009 All-Star workout in St. Louis, which was married together with a beaming Frank Robinson from about a half-century before.
"That was one of the earlier moments when we realized this really started to work, and we knew this could be something special," Mallory said.
He and his team photographed Studio 42 "a million ways" and used Flame software for "infinitely layerable digital compositing" after selecting appropriate footage. That's how Walter Johnson shakes hands on the field with fellow Hall of Famer Sandy Koufax, even though the Big Train died about a decade before Koufax made his Major League debut with the Dodgers. That's also how Mike Schmidt shakes hands with a young Henry Aaron, an interesting juxtaposition of 1974 National League All-Star teammates.
"We did a lot of work with a company called Big Studios in Canada, and had them rotoscope about 40 clips," Mallory said. "After we had composited the raw clips, and figured out what relationships would take place, we had to get the players removed from the environment they were in. We had to get somebody to hand-cut black-and-white images or mattes, frame-by-frame, with each player."
There were two especially difficult challenges:
1. Getting Jackie Robinson to run out of the Studio 42 dugout in a believable manner.
"We did a little CGI work to rebuild part of the dugout that's actually in Studio 42 so he was actually behind a little bit of fence, making it appear [that] the fence was in front of him and it was as believable as possible," Mallory said. "That was a big one. ... We shot the dugout again and again, did a few more things here, and hopefully got it to look as realistic as possible."
2. Pairing black-and-white film with color videotape to show in HD.
"A lot of the older players were shot on film, and a lot of the new players were shot on videotape," Mallory said. "So the quality of the film is so grainy compared to videotape and then HD, and the trick is, 'How do you marry the film stuff with players from the '70s and '80s who were shot on videotape, so there isn't so much of a contrast between the two mediums.'
"We talked about colorization for about 10 seconds and ruled that out. We're not trying to fool anybody."
Petitti chose the music track: "Lake Michigan" by Rogue Wave, courtesy of Brushfire Records. Costas' narration gave the production the weight it needed. At least one legend test-watched it. Lou Piniella viewed the spot -- and didn't even notice a late-era Junior Griffey running past him in his old form as Kansas City's 1969 Rookie of the Year.
"I wasn't sure what to expect, but it definitely exceeded my expectations," Petitti said.
Among the other players included in the spot: Ted Williams, Mike Piazza, Dizzy Dean, Eddie Mathews and Johnny Bench.
The party returns now with Spring Training and the third season for MLB Network, where more than 55 million households can see the National Pastime all the time. Everyone is here, all in one place -- even if it requires a lot of technical magic to make it happen.
"It's a fun place, respects the game, shows you the current guys and the old guys," Petitti said. "We're trying to give you something in baseball you're not used to seeing. You want people to feel good about the game."