Armed with a flashlight and the full moon’s brilliance, fearless trekkers will explore intriguing tombstones and the haunting catacombs with Green-Wood historian Jeff Richman. Look out for the spirits of illustrious cemetery residents like Boss Tweed, Louis Comfort Tiffany, Leonard Bernstein and Jean-Michel Basquiat. The skeptical can simply enjoy the frisson of nighttime skulking, accompanied by live accordion music.