The Prince George Ballroom

What Everyone Does…
Grand Central Terminal
A tour of the Beaux Arts icon with its 1998 renovation architects. E 42nd St at Park Ave. Sat 4 at 11am, 1pm; reservations required.

What you should do instead...
The Prince George Ballroom
Beyer Blinder Belle Architects & Planners, the force behind the Grand Central Terminal and Ellis Island restorations, has brought this ballroom back to life with the help of Parsons students and various nonprofits. 15 E 27th St at Fifth Ave. Sun 5 noon–5pm.

And hey, while you're there...
Ballroom manager Jonathan Rives loves the “urban barbecue” at nearby Blue Smoke (116 E 27th St between Park and Lexington Aves, 212-447-7733). After pigging out, head downstairs to the Jazz Standard (212-576-2232, jazzstandard.net); the Sunday 5 lineup features Antonio Sanchez & Migration (7:30 and 9:30pm, $25).

The Octagon

What Everyone Does…
Guggenheim Museum
A tour and Q&A with museum staff and the project manager for the restoration of Frank Lloyd Wright’s curvilinear masterpiece. 1071 Fifth Ave at 89th St. Sat 4 at 2pm; reservations required.

What you should do instead...
The Octagon
This 19th-century insane asylum on the northern tip of Roosevelt Island was restored and given a new purpose as an eco-friendly apartment building. The site features an art gallery, ecological park and green building exhibit. Join preservationists and developers for a Q&A session. 888 Main St, Roosevelt Island.

And hey, while you're there...
Check out the 50-foot-tall beacon o’ brightness at nearby Lighthouse Park; it was built by island convicts in 1872.

One Sixty Glass

What Everyone Does…
Tom Otterness Studio
Meet the man behind the ubiquitous bronze sculptures. 96 4th St at Bond St, Carroll Gardens, Brooklyn. Sat 4, Sun 5 at 10:30am, 1, 3pm; reservations required.

What you should do instead...
One Sixty Glass
Glassblowing demos take place Saturday 4 at 11am, 1 and 3pm and Sunday 5 at 1pm. 160 Berry St between North 4th and 5th Sts, Williamsburg, Brooklyn.

Or try this...
The Dumbo Debates
Hike the pedestrian walkway on the Brooklyn Bridge to see Trong Gia Nguyen’s project, part of Flux Factory’s “Living Room” series: Obama and McCain philander on a secret rooftop, swilling booze and yakking politics. Bring your own binoculars, or borrow theirs. Sat 4, Sun 5 11am–6pm. For more Flux–OHNY action, including rooftop camping, public toilets turned terrorist cells and a game of hide-and-go-seek at the Arsenal, visit fluxfactory.org/living-room.

Green-Wood Cemetery

What Everyone Does…
Cathedral Church of St. John the Divine
A vertical tour of the Romanesque and High Gothic structure. 1047 Amsterdam Ave at 112th St. Sat 4 noon, 2, 3, 4pm.

What you should do instead...
Green-Wood Cemetery
These hills will be anything but dead when cemetery historian Jeff Richmond takes visitors on the Angels & Accordions tour. Choreographed by Dance Theatre Etcetera’s Martha Bowers, performers greet walkers as they journey through mausoleums, chapels and catacombs usually closed off to the public. 500 25th St at Fifth Ave, Sunset Park, Brooklyn. Sat 4 noon, 3:30pm, reservations required.

And hey, while you're there...
Pull up a chair at Belachan (6102 Seventh Ave at 61st St, Sunset Park, Brooklyn; 718-492-9088), a cash-only Sino-Malaysian restaurant serving roti canai and a host of spicy vegetarian dishes. Afterward, tool through the park that gave this nabe its name: The 24.5-acre space has sweeping harbor and skyline views, basketball and handball courts, and impressive student-painted murals.

READY TO GO? Open House New York runs Saturday 4 and Sunday 5. Call 212-991-6469 or visit ohny.org for detailed info and reservations.