Get ready to take a look behind the curtain at some of New York’s most-hidden places.

Open House New York — which returned Friday and lasts through Sunday — gives people rare access to more than 150 spots across the city that are usually closed to the public.

The annual festival allows crowds to see things that many, even lifelong residents, have never seen before in the city. Some of the most historic, exclusive and uniquely New York spaces are free to explore.

“Our tours range from historic houses to penthouses, art galleries, sanitation spaces,” said Kristin LaBuz, the executive director for Open House New York.

She says the event “gives New Yorkers a hall pass to explore the city.”

There are 300 locations in all, with half of those being free to check out throughout the weekend. Those interested can head to the New York Sign Museum, to see historic signage from over the years across the city. Or try their hand at an ancient craft at Pellettieri Stone Carvers Academy in the Garment District.

One of the new sites to see this year: One of three private rooftop gardens at Rockefeller Center.

“You are going up to these spaces that are never open to the public and seeing entire Rockefeller Plaza, the art deco facades of the building,” said LaBuz.

Looking for some real old-school New York? Head to a private event space in the South Bronx called La Bodega.

“I want you to walk in and be like, wow. You’re not expecting this,” said Jonathan Guerrido, who co-owns the spot. “This is an homage to nostalgic New York City…I want you to feel transported. That’s why you have the velvet curtains.”

The space is lined with settings familiar to any New Yorker, recreating different streets that could be found across the five boroughs in the past. La Bodega has played host to celebrity birthday parties, music videos, comedy shows and community programs.

“We built this for the culture of the city, for the South Bronx especially, and to ignite people, make them feel the nostalgia feel that creativity come alive,” Guerrido said. “It’s a huge honor to be part of this event, Open House New York, to be featured among so many iconic venues. It just gives everyone the opportunity to see what’s happening from every walk of life and experience something you’ve never experienced before.”

At Marcus Garvey Park, visitors can walk all the way up the hill, up to the top of the Mount Morris Fire Watchtower, and ring the 3,000-pound bell of the NYC landmark while soaking up the views of Harlem.

“New Yorkers are so proud of their city and so curious about their surroundings to see how everything works, but hey, also love bragging rights right? They love being places no one else gets to go so we check all three boxes,” said LaBuz.

Open House New York goes until Sunday, Oct. 19.