Hilltop Dog Park sits inside the Hilltop Reservation, a large nature preserve on the Second Watchung Mountain that was once the site of a tuberculosis sanatorium. The dog park itself is fully fenced and divided, about a quarter-acre for small dogs and a half-acre for large dogs, with a decorative entrance gate, brick paved pathway, play apparatus, benches, water fountains for people and dogs, and waste stations. It's the fourth off-leash park in the Essex County system and draws visitors from four surrounding municipalities.