Circa Las Vegas To Open The Largest Sportsbook In The World In 2020 On Thursday night, Derek Stevens introduced his newest casino project in Sin City. Circa Las Vegas will open in downtown Las Vegas in late 2020. The vision for the entire casino sounds great, but the Michigan native and huge sports fan saved the best for the sportsbook. The Circa Las Vegas Sportsbook will be the largest in the world. The sportsbook will have two floors of stadium seating.