A live round was found inside an 18th-century cannon that had been on display at the Central Park Conservancy, police said.

A piece of rust was removed during routine cleaning, exposing the cannonball, police said.

“We silenced British cannon fire in 1776 and we don’t want to hear it again in Central Park,” NYPD spokesman Paul Browne said yesterday.

The cannon came from a British Royal Navy ship.