Union Grounds was a baseball park located in the Williamsburg section of Brooklyn, New York. The grounds opened in 1862, its inaugural match being played on May 15.[1] It was the first baseball park enclosed entirely by a fence, thereby allowing proprietor William Cammeyer or his tenant to charge admission. This permitted paying customers to watch the games from benches in a stand while non-paying spectators could only watch from embankments outside the grounds.[2]