The 2020 Democratic presidential candidate and former vice president spent about 30 minutes at the New York City tavern. He mingled with patrons, went behind the bar and took selfies with visitors.
"When people had the courage to come out and stand up and speak, say who they were, all of a sudden people realized, 'Whoa, these folks are just like me,'" Biden said. "And I'm really proud of the folks in here and the courage it took for what they did."
The bar is a reincarnation of the original Stonewall, which was the site of an infamous police raid in 1969.
At the time, police crackdowns on gay bars were commonplace, but at the Stonewall Inn, patrons and protesters resisted the officers.
Street protests continued for several days.
The bar is marking the anniversary of the uprising on June 28.
A park across from the Stonewall Inn is now a national monument to gay rights.
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