What a lovely day for a stroll along the . . . yikes!

The Brooklyn Bridge became so crowded with pedestrians, cyclists and illegal vendors on a 50-degree Saturday afternoon that cops were called in to manage the traffic.

“I walk the bridge for exercise almost every day and never in my life have I seen it that packed with people,” said James Fiorentino, 67, of the Lower East Side.

“At first I thought there was some march or protest today, but I didn’t see any posters.”