It is a head-spin development from the fight the 76ers have lodged over the last two years when it sought to build a new arena in Chinatown and close to the city’s center, and as it went to battle with Comcast,

Plans to build an arena for the Sixers in Center City have fallen through, and the team plans to stay in South Philadelphia, sources close to the negotiations say.

The stunning reversal comes as a relief to critics of the plan to put a $1.3 billion arena near City Hall at the edge of Chinatown. Mayor Cherelle Parker on Monday called the proposal “a win, win, win,