The New York City subway is the one of the largest and oldest metro systems in the world, moving more than five million people under and around the city every weekday. Though New Yorkers often grumble that its age is starting to show, the system has also accumulated its fair share of secrets in its 115-year history. 

From abandoned stations to hidden art displays, the secrets run the gamut from cute and quirky to fodder for conspiracy theories. Some of these oddities are art displays you can only see while riding the trains, and others—such as the city’s holiday train—are seasonal opportunities to travel, seemingly, through time itself. From Brooklyn boulevards to leftover bits of broken dreams, explore the subway’s hidden treasures.