Wikimedia Commons
Union Grounds, a ballpark located in Brooklyn, New York, hosted its first contest on May 15, 1862. Enclosed entirely by a fence, Union Grounds became the first ballpark to charge admission to watch the game. Non-paying spectators, meanwhile, could watch the game from embankments outside of the grounds (although, I imagine the view wasn’t as good). The Brooklyn Eagle described the ballpark:
The buildings occupied last winter are left standing, used pretty much for the same purposes as them.[sic] Near these a long wooden shed has been erected, capable of accommodating several hundred persons, and benches provided for the convenience of the fair sex… Several acres more have been added to the enclosure, which is fenced in with a board fence six or seven feet in height. On the southeast corner a large and commodious club house has been erected, containing accommodations for three clubs. The field is now almost a perfect level, covering at least some six acres of ground, all of which is well drained, rolled, and in a few weeks will be in splendid condition… Several flagstaffs have been put up, from which floated the banners of the clubs o’er shadowed by the nations’ ensign.
Brooklyn Public Library