• Capital One Arena's new sportsbook opened to the public on Wednesday.
• The sports industry will be watching to see to see if this new model can be applied in other cities.
• Sports gambling is helping make up for losses in revenue due to the pandemic.

The William Hill Sportsbook opened Wednesday inside the Capital One Arena in Washington, marking the first sportsbook to operate inside of a U.S. arena.

The development shows the "breathtaking" change in the relationship between sports leagues and team ownership and sport betting companies over the past several years, said Tom Reeg, CEO of Caesars Entertainment.

Other sports owners are watching closely to see if a similar model could be applied inside their arenas.

"This feels very natural to be in this building and to be able to walk into the arena and into a venue like this, to place bets, and I think you're going to see this continue throughout the country," Reeg said, in an interview with CNBC.

Smack dab in the middle of the nation's power center, the two-story, 18,000-square-foot venue will serve as a 365-day-a-year destination for bettors. Gamblers will have access to up to 20 betting windows, and over a dozen self-serve kiosks to place wagers.

The Sportsbook also features a state-of-the-art broadcast studio that will host Monumental Sport's "By the Book" sports betting show and the new facility boasts dining from Michelin-rated Chef Nicholas Stefanelli.

In the three years since the U.S. Supreme Court overturned the Professional and Amateur Sports Protection Act, the sports world has been turned on its head. The law, also known as PASPA or the Bradley Act, prohibited most states from offering legal sports wagering,

In 2017, NFL Commissioner Roger Goodell held a news conference after an owners' meeting in Phoenix and doubled down on the league's and owners' opposition to legalization.

"I think we still strongly oppose legalized sports gambling," Goodell said at the time. "The integrity of our game is number one. We will not compromise on that."

Today, many of the same people that opposed sports gambling, see it as a new frontier, especially as pandemic-related financial losses continue to pile up. Sports teams have also found that betting not only brings in more cash, but more engaged fans.

Monumental Sports and Entertainment owns multiple Washington-area sports teams, including the Capitals and the Wizards. Its CEO, billionaire Ted Leonsis has pushed hard for sports leagues and owners to embrace legalized sports betting.

"You look around this Sportsbook," Leonsis said. "It feels like day trading, right, for the millennial and Gen Z, very highly educated, highly compensated person that [can] come and buy season tickets — buy tickets for thousands of dollars — to now have a rooting interest in, to be able to come in and enjoy how all this data is presented. It's very synergistic for the leagues and teams."

The William Hill Sportsbook is the only new business to open in downtown Washington during the pandemic, and the money it has generated has helped boost the district's revenue.

Caesars has a growing number of ventures inside athletic facilities. Its deal with the Arizona Diamondbacks gives it market access to mobile betting and exclusive sponsorship opportunities. Caesars has also finalized a multiyear agreement with Major League Baseball to become an authorized gaming operator of the league, in addition to its recent deal with the National Football League.

The partnership deals are part of a larger industry trend as professional sports leagues embrace sports betting. The National Basketball Association has made various deals with The Score, DraftKings, William Hill and MGM Resorts, among others.

And the NFL — whose commissioner was so staunchly opposed to legalized sports betting — now has three official gaming partners, DraftKings, FanDuel and Caesars.

In February, the NHL added its fourth sports betting partner with PointsBet, taking a equity stake in the company.

"The reality is you've got to adapt to the way your customer wants to consume your product, and sports betting really fits where the world is today. ... We want constant activity, constant action, and sports betting feeds right into that," said Reeg.