This weekend, 256 public and privately-owned sites across New York City will open their doors to thousands of architecture and history nerds for the 13th annual Open House New York (OHNY) Weekend. All sites are free to visit, though some require registration in advance.

Gregory Wessner, executive director of OHNY, said the event is an “opportunity to get an audience to look at the city through different disciplinary lenses.” This year, 1,200 volunteers will staff 256 sites. Wessner explained the selection criteria: sites are evaluated for their architectural, cultural, and historical significance; location; proximity to public transportation; period, style, and typology. Last year, OHNY Weekend attracted approximately 75,000 visitors over two days. 80 percent of those visitors were New Yorkers.

Given the depth and breadth of the offerings, it’s impossible to privilege one site over another, though Wessner said he’s particularly excited about City Hall. City Hall, he believes, “represents what’s great about OHNY. It represents the seat of government, which most of us don’t get to go into, and welcomes the public to go in and look around.” New York’s Beyer Blinder Belle renovated the palatial 1812 structure this year.

A little-known architectural mecca is Bronx Community College. From 1959–1970, New York University (then owner of the campus) commissioned Marcel Breuer to design four buildings. DOCOMOMO New York/Tri-State will lead tours of Breuer’s buildings on Saturday and Sunday. Also on campus: the Beaux-Arts Gould Memorial Library and Hall of Fame (Stanford White, 1900) and North Hall and Library (Robert A.M. Stern, 2012).

Though the weekend is the group’s biggest event, OHNY operates throughout the year, organizing tours and talks to encourage dialogue around major issues affecting the city’s built environment. The Final Mile is a yearlong exploration of the “challenges and choices for an equitable and resilient food system” in New York. Food manufacturing, Wessner stated, is the fastest growing manufacturing sector in the city, and drives real estate development (think Smorgasburg and Chelsea Market). Tomorrow, Friday, OHNY is leading tours of food manufacturing facilities as a lead-up to the weekend.

Visitors should check the OHNY Weekend for updates ahead of their trip. See the gallery below for more images of featured sites.