Most visitors and residents of New York City are aware of the big flashy things to do. Take a stroll through Central Park, visit the Empire State building, take the ferry out to the Statue of Liberty, ride a wooden coaster on Coney Island… the list goes on and on.

But New York is a large old city with a multitude of secret underground attractions – both literally and figuratively. From the time of the Revolutionary War, you’ll find old outposts used to watch out for the British. From the Gilded Age, you can find ruins of once luxurious hotels and buildings. As a throwback to Prohibition, there are even a number of speakeasies that require a password – or other connection – to get in. And while New York City has plenty of famous museums – the Metropolitan Museum of Art, the Natural History Museum, the Museum of Modern Art – there are also a multitude of hidden museums to discover, such ass the Trash Museum and a minuscule museum that only allows three visitors at a time. And let’s not forget New York City’s massive subway system, which hosts a multitude of literal underground sights to behold.

Check out the list below for fifteen secret underground things to do in New York City.

15. Please Don’t Tell

Located near the East Village, the aptly named Please Don’t Tell is a speakeasy style bar which requires a bit of subterfuge to enter. You have to find a phone booth near a restaurant called Cliff Dogs. After picking up the phone and pressing the buzzer, you’re let in to a minuscule bar. In this intimate space, you can order either cocktails or food from next door’s restaurant Cliff Dog’s. You can enjoy such drinks as the Staggerac, made with bourbon and absinthe. Or give an original cocktail a try — there’s even one made of bacon flavored bourbon and maple syrup.

14. Bohemian

Bohemian is another speakeasy style bar in which you need a phone number or referral for entry. It’s located in a building that was once owned by Andy Warhol, and its intimate design models the inside of an apartment, with couches and seats. As a members only bar, its appropriately small. The theme is a fusion of both Asian and America, with cocktails that allude to both, such as . You can also enjoy small plates that consist of short rib sashimi or burgers with homemade pickles. The background plays jazz or Japanese music.

13. Ramble Cave

Did you know there’s a cave in the urban streets of New York? In Central Park, by the 79^th Street Traverse, you’ll find it. At one point it was known as the ‘Indian Cave’ due to potential evidence of Native American inhabitants, before becoming known as the “cave” and eventually “the Ramble Cave”. Unfortunately, it’s sealed off. The entrance was bricked up and covered with dirt to give it the appearance of a hillside in the ’30s. You can still spot the steps near the cave, but otherwise there is no telltale existence of this natural wonder… a secret underground spot in New York City.

12. Roosevelt Island Smallpox Hospital Ruins

This hospital is exactly what it sounds like – a once operational hospital that now sits in ruins. Opening its doors in 1856 when Roosevelt Island was called Blackwell’s island, it was designed in the Gothic Revival style by architect James Renwick. The hospital treated patients infected by smallpox, and it was located on the south of the island as a method of quarantine. There was also a charity ward located here. But the hospital eventually fell into disuse, and was soon announced as an official New York City landmark. It’s worth making the trek over to Roosevelt Island to take in this ruin from the city’s past.

11. Featherweight

Want to check out an underground bar in Brooklyn? Head over to Williamsburg, where you’ll find Featherweight. In order to enter, you’ll have to enter the adjoining bar Sweet Science, and go through the passage in its boiler room. You’ll find a tiny bar dimly lit with chairs and booths. Enjoy an extensive cocktail list such as High Roller, which combines champagne and Antica Carpano; or Witch’s Brew, a jujube infused fin. As you enjoy your cocktails, imagine a time past during the Prohibition Era, when a speakeasy was the only way to (secretly) have a drink.

10. Track 61

New York is known for its extensive underground system, so it should come as no surprise that there are secret underground abandoned subway stations. Track 61 is one such station. Located beneath the swanky Waldorf Astoria hotel, it’s possibly still being used today to transport super important people – including presidents. The track was rumored to have been used by Franklin D. Roosevelt, who used it to hide his polio. It was also allegedly used by George W. Bush when he had meetings at the Waldorf. The station is currently covered in layer of dirt and grime, but you’ll find an old trail car still tucked away in the powerhouse.

9. Mmuseumm

Mmuseumm (yes, it’s spelled like that) is a minuscule museum, that can literally only fit three people at a time. You’ll find it in Tribeca, located inside an unused freight elevator on Cordlandt Alley. It contains various nicknacks about the modern world, and you can find a whole array of random items here. There are items such as Taco Bell wrappers, toy ponies, scatterings of cornflakes, and Trump branded merchandise. This all may seem scattered, but there are themed exhibitions here. Past exhibitions have included: Paper Works found in Copying Machines, and Homemade Weapons of Defense.

8. Houdini Museum

Finding the Houdini Museum can be a bit like performing a magic trick – it’s not easy to find. You’ll have to make your way to 33^rd Street. Now find an awning near the subway stairs and take an elevator to the Houdini Museum, which is located inside the magic shop Fantasma. The museum displays artifacts and documents related to Houdini. You can take in personal letters, news clippings, and posters from his magic shows. There are also dozens of handcuffs worn by Houdini to perform his famous stunts, in addition to straitjackets. Whether you’re a fan of Houdini or just curious, it’s worth checking out this museum – if you can find it.

7. Hidden Tropical Rainforest

This is a pretty cool and unexpected find in New York – a hidden tropical rainforest. It’s located in a building that was built in 1967 as the location of the Ford Foundation – Henry and Edsel Ford’s charity organization. The building is made of both steel and glass, and serves as a sort of tropical greenhouse. This is how the “rainforest” can exist. You’ll find magnolias, dwarf shrubs, trees, and even garden terraces. It’s hard to believe that something like this can exist in the urban jungle of New York City; and it is quite a sight.

6. New York Marble Cemetery

Its doubtful that even residents are aware that there’s a tiny burial ground in New York City’s East Village. But alas, there’s a cemetery of over two thousand tucked away there; the oldest public non sectarian cemetery in the city. The burials took place over the course of a century, from 1830 and the last in 1937. The cemetery earned its name from the underground vaults made of marble. There aren’t identifying gravestones; instead, the names of the deceased are on plaques in the walls. As a literal underground spot in New York City, you should definitely give this cemetery a brief visit.

5. Clocktower Gallery and Machinery Room

A relic of New York City’s Gilded Age, the Clocktower building was built in 1898 by the architects McKim, Mead and white. It once held the city’s largest mechanical clock. With over a dozen gears, attached to a hammer that struck a bronze bell, that was over five thousand pounds. Like many buildings from the 19^th century, it eventually fell into disuse. But it was renovated it the 70s by Marvin Schneider and Eric Reiner. Schneider is now the clock master, and the clock is once again working. You’ll find it on Leonard Street in downtown Manhattan.

4. Trash Collection

Nelson Molina, a sanitation engineer, began picking up items from his pickup route decades ago. Soon, coworkers joined in, until there was a collection in his garage. The aptly named Trash Collection is indeed a bit of a secret – you have to contact the city to see it. Amongst the collection, you’ll find items such as fake flowers, exotic lamps, plastic Furbys, and even a Michael Jackson shrine decorated with guitars. With no formal museum type exhibit layout, the items are organized by theme. So if you’re feeling curious about the castoffs of a massive city, head over the the Trash Collection.

3. Knickerbocker Hotel (Secret Entrance)

The Knickerbocker Hotel was a grand hotel during its time, built by John Jacob Astor in 1906. It had hundreds of rooms, and there was enough space in the bars and restaurants for thousands of patrons.

It was shut down in the 20s, and became the home of Newsweek’s headquarters and garment showrooms. It’s hard to find, but there’s a white door located on the eastern section of Track 1’s platform at the 42^nd Street station that was a secret entrance to this once luxuriant hotel. You’ll see a faded sign above it which says Knickerbocker, a remnant from another time.

2. 6 1/2 Avenue

It’s hard to believe that there’s a secret street in New York City, but it’s true. Head to Sixth Avenue. In between Sixth and Seventh Avenue, between West 57^th and West 51^st, you’ll find 6 ½ Avenue. The Department of Transportation gave the street official signposts in July 2012.The street is known as a Privately Owned Public Space – such spaces began in the 60s as incentives for property developers to add public spaces to their buildings. The half street is a useful way of cutting corners to get through the city without having to pass the avenues.

1. The Blockhouse, Central Park

New York City is old – predating America itself old. So it should come as no surprise that there are relics from the Revolutionary War in the city. In Central Park you’ll find one such relic, the Blockhouse. It’s the last of fortifications built along the north of the park to defend against the British during the Revolution. After Cleopatra’s Needle, it’s the second oldest building in the park. It’s hard to get to, tucked away in a wooded area that is rugged and high. But if you can get to it it overlooks Harlem Meer.