You might expect a city noted for its skyline to be a hotspot for viewing great architecture, but for every notable landmark that’s accessible to the public, there are as many spectacular New York sites where access is limited.

That picture changes every October when Open House New York, a nonprofit that for years has been devoted to “inspiring, engaging and educating the public about New York City’s architecture, design and cultural heritage,” makes sure the city’s most amazing structures are not just seen, but experienced by everyone.

On Oct 12 and 13, the organization launches its 11^th annual OHNY Weekend, a citywide event that throws open the doors to nearly 400 spaces throughout the five boroughs at little or no cost, including private residences, along with notable churches, museums, schools and other architectural treasures. If you’ve ever marveled at a building or wondered, “what’s it like in there?” chances are it’s on the list of the OHNY Weekend’s sites. In addition, there are many tours and talks with architects, designers and historians.

Due to the popularity of OHNY Weekend, several of the most fascinating sites and tours require advance registration as well as a $5 fee; but there are also many “open access” sites that are free of charge. Why pay when you can go free? Lines at the free-for-all spots can be long; picking your RSVPs can guarantee you a spot.

Plan your weekend

If you plan to visit RSVP-only sites, it’s a good idea to visit the OHNY site and make reservations as early as possible. (Head-of-line privileges for all sites can be obtained by purchasing an OHNY Weekend Passport, which costs $150.) If you’re picking open-access sites, know that lines can form early. Either way, wear comfortable shoes!

High among the most anticipated stops this year will be the private homes of more than 20 designers who are graciously allowing OHNYers into their digs. What else to check out? Check out our borough-spanning roundup of OHNY Weekend fare.

RSVP-only Sites 

Among those that have available spots at this time are:

• the neo-Romanesque New York Academy of Medicine in East Harlem, where tours will take in the medical symbols that are a feature of the building along with private reading rooms (click here to reserve)
• the wonderfully ornate Ukranian Institute of America, housed in the Upper East Side mansion once owned by oil tycoon Harry F. Sinclair (click here to reserve)
• the Louis Armstrong House Museum in Corona, Queens; tours are on the hour (click here to reserve)
• Alice Austen House on Staten Island, the 18th-century farmhouse-home of the prolific photographer (click here to reserve).

Click here to see all RSVP-only sites.

Manhattan Open Access

Kushner Studios House

This might be the last time visitors get to see this three-story 1928 carriage house in its current guise. The former home of famed event planner Robert Isabell, it features 30-foot-high ceilings, glass catwalks and eccentric interior design. Current owner, architect Adam Kushner, will be redesigning it soon; at 1 and 3pm he’ll be offering guided tours and talks.  This OHNY site is part of Interior Design Magazine’s Designers’ Open House.

Where 16 Minetta Lane
When  Sat 12, 10am-5pm
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M&B Building

Following its recent glass-sheathed makeover, this structure (long title: The Manufacturers and Builders Building) sits at the heart of NYC’s Decorator and Design district and is a new stop in the OHNY Weekend. Architects will give tours throughout both days.

Where 201 E 57th St
When Sat 12 & Sun 13, noon-4pm
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Lighthouse Tender LILAC

LILAC is a steamship that was built for the U.S. Lighthouse Service and served the Coast Guard by carrying supplies to lighthouses and maintaining buoys until 1972. It’s the only surviving steam-powered lighthouse tender in America, and this is a rare opportunity to explore its many nooks and crannies, including the inner workings. The going can be a little rough for anyone with mobility issues.

Where Pier 25, Hudson River Park at N. Moore St
When Sat 12 & Sun 13, 1 – 7pm; tours throughout
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Grand Lodge of Masons

There’s scarcely a surface in this ancient organization’s central meeting place that is not covered with ornate inscriptions and symbology. Lines can be long, but a tour of the normally closed-to-visitors building offers both a visual feast and interesting insights – well worth the wait.

Where 71 W. 23rd St.
When Sat 12 & Sun 13, 11am-2pm
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Marble Collegiate Church

From its impressive bell tower  to its Tiffany stained glass windows and marble exterior – built from solid blocks shipped down the Hudson from a Hastings quarry – this Romanesque Revival church is a grand gesture. Its walkable labyrinth, based on one at the 13th-century Chartres Cathedral, is a new addition. There will be tours throughout the afternoon.

Where 1 W. 29th St.
When Sunday 13, 2-4pm.
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National Academy Museum and School

The turn of the century-style former mansion of philanthropist Archer M. and sculptor Ann Hyatt Huntington has been renovated to create a series of dynamic museum galleries.

Where 1083 Fifth Ave
When Sat 12 & Sun 13, 11am-6pm; tours at noon, 2 and 4pm (30 people max)
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Center for Architecture

The Center plays host to the OHNY Weekend Family Festival, an all-ages event with great activities for grandkids.

Where 536 LaGuardia Pl
When Sat 12 & Sun 13, 11am-3pm
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Bronx Open Access

Edgar Allan Poe Cottage and Visitors Center

Nothing macabre about the quaint farmhouse, surrounded by trees, where the author of “The Raven,” “The Cask of Amantillado” and “The Masque of the Red Death” spent his final years. The cottage has been restored to its original appearance, with authentic period furnishings.

Where 2640 Grand Concourse and E. Kingsbridge Rd.
When Sat 12 & Sun 13, 10am–4pm
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Woodlawn Cemetery

Admire hundreds of private mausoleums by great designers like McKim, Mead & White, Tiffany, John Russell Pope, and Hunt & Hunt, that dot meticulously planted parkland.

On Saturday from 7-8pm the Amateur Astronomers Association will be offering a unique opportunity to do some urban stargazing at Woodlawn. The event starts at 7 in the Woolworth Chapel with a slide presentation and Q&A about what you’ll see in the sky; from 8 to 10pm, join a hike to the crest of the Webb family plot, where you can gaze through telescopes and high-powered binoculars.

Where Jerome Avenue Gate House (approx 3700 Jerome Ave/Bainbridge Ave)
When Sat 12 & Sun 13, 8:30am-5pm; stargazing at 7pm.
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Bartow-Pell Mansion Museum

Pelham Bay was considered a country getaway when this spacious mansion was in use in the 19^th Century. This weekend, costumed docents will lead guided tours of the period Greek Revival rooms and formal gardens; there’s also an exhibition of antiquarian gardening books.

Where 895 Shore Rd at Hutchinson River Pkwy
When Sat 12 & Sun 13, noon-4pm; lecture on Sun 4:30-6pm
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Valentine-Varian House

Reaching back to the American Revolution, this two-story 1758 farmhouse, built out of the native stone that lay on the land where it stands, is the borough’s oldest.

Where 3266 Bainbridge Ave
When Sat 12, 10am-4pm; Sun 13, 1–5pm
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Brooklyn Open Access

Kathryn Scott Design Studio Brownstone

By restoring its Italianate features and incorporating family heirlooms, internationally renowned designer Kathryn Scott has performed remarkable renovations to the 1860 brownstone she shares with artist Wenda Gu.

Where 126 Pierrepont St
When Sat 12 & Sun 13, 9am–5pm
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BRIC Arts/Media House and UrbanGlass

This storied corner spot, once home to the Strand Theater, now houses a new 40,000-square-foot multipurpose performing arts center as well as an exhibition space for creative glassworks. The architect responsible for the renovation gives tours at 10:30am and noon.

Where 647 Fulton St at Rockwell Pl
When Sat 12 & Sun 13, 10am–10pm

Brooklyn Army Terminal

It was the largest military supply base in the US during WWII, but these days this sprawling terminal – a cutting-edge industrial design of its time by Cass Gilbert – is repurposed as an industrial complex and home to both modernists and futurists. It’s off the beaten path, but well worth the effort.

Where 140 58^th St
When Sat 12, 11am–5pm
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Queens Open Access

TWA Flight Center

Rarely open to the public and rumored to be slated for rebuilding as a hotel, Eero Saarinen’s masterpiece of 60s modernism has been beautifully restored over the past five years.

Where JFK International Airport, Jamaica
When Sun 13, 11am-4pm
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King Manor Museum

The farm that was home to New York’s first senator, Rufus King (also an author of the Constitution), is now the grounds of King Park.

Where 150-03 Jamaica Ave
When Guided tours Sat 12, 1–4:30pm; Sun 13, 1–2:30pm
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Staten Island Open Access

St. George Theatre

The historic vaudeville-era theater is the epitome of elaborate baroque style, both inside and out, with its ornate windows, grand staircases and larger-than-life paintings of bullfighters.

Where 35 Hyatt at St. Mark’s Pl
When Sat 12, 10am–2pm; tour 12pm
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Click here to see a complete, searchable listing of all OHNY sites.