The secret of this lovely little park at the foot of Broadway isn’t what’s inside the park but what surrounds it: that ordinary-looking iron fence. It’s a national treasure. It was erected in 1771. It was this very fence that an excited crowd of New Yorkers attacked with crowbars on July 9, 1776, breaking off kings crowns that decorated the fence posts. The Declaration of Independence had just been read aloud in New York for the first time. The Sons of Liberty swung the crowbars and then attacked the statue of George III that stood here. When they were through, they took the smashed metal and melted it into cannonballs for George Washington’s new army. You can still feel the rough spots with your own hands.