Attention, Mixed-up Files fans. At New York’s American Museum of Natural History, the real fun begins after closing time. Bring your own bedroll.

Buff Strickland
| Credit: Buff Strickland

My 11-year-old and I arrive at the American Museum of Natural History in Manhattan a little before 6 on a Friday evening, just as the last day visitors are straggling out. Sleeping bags slung over our shoulders, we head for the Hall of Ocean Life, the cavernous room with the big blue whale suspended from the ceiling. "A bunch of thrill-seeking girls," as Ike puts it, have already unfurled their bedrolls before the almost life-size squid and whale diorama—a depiction of undersea combat legendarily scary to generations of schoolchildren. We stake our claim to cots in front of walruses basking on the ice. Trouble is, while we lie beached on our cots, testing out our new sleep- ing arrangements, people keep walking by and saying "Look at the walruses!" so often I begin to think they’re talking about us. Well, me, actually. This is what comes of being a 46-year-old woman wearing what amounts to sleepwear in public.

Not that we’ll be doing much sleeping. A couple of years ago, museums around the country started offering overnight programs to satisfy the public’s apparently widely held desire to be locked in a drafty cultural institution after hours. This is a dream I myself have shared since the age of nine, when I read From the Mixed-up Files of Mrs. Basil E. Frankweiler, the delightful novel about kids who take up residence in New York’s Metropolitan Museum of Art for a week. Last year, when the American Museum of Natural History announced its own overnight, I knew that was where I wanted to camp. Ike and I could drive up from D.C. and pay less for a stay at the museum than we would for a hotel room. I promptly enrolled us—and only later remembered that the older I’ve gotten, the fonder I’ve become of spending the night in a bed. Ike and I wouldn’t exactly be alone in the museum, either—there’d be 300 other people hunkered down with us, and some of them, surely, would snore. Was this going to be more like a night in a Red Cross relief center than a fulfillment of my childhood fantasy?

After a blessedly brief rundown of instructions from an upbeat museum employee—no food or drink in the exhibition halls, no Heelys, lights out at midnight—we’re free to stroll through the warm-as-the-tropics Butterfly Conservatory, where a luna moth perches on my shoulder. On a scavenger hunt in the darkened fossil rooms, the play of competing flashlight beams makes me feel as if I’m at Studio 54. There are carts enticing us to enact experiments—such as dropping a metal ball into sand to simulate a meteor and the crater it makes—or to handle animal bones and fur. But the best part is the Frankweiler-ish experience of wandering around on our own. True, the building is echoey, so you hear other people even when you can’t see them. But you are sharing the vast space with a fraction of the 5,000 to 10,000 visitors that the museum gets on a weekday. At one point, Ike and I end up alone in the Hall of African Mammals. It feels majestic and hushed—and spooky. What are we doing here at 9 at night?Where is everybody?Did that lion twitch its tail?

By 11:30, when they start showing a movie about dolphins on all the screens in the Hall of Ocean Life, I’m bleary-eyed, and even Ike is ready to turn in. That’s when I realize we are at a very large slumber party. You know how much futile time you spend telling kids at a sleepover to go to sleep?And how much giggling and shushing you hear in the meantime?Well, imagine that multiplied by hundreds. I fall into a fitful sleep, then an hour or so later come to and find that maybe half of the kids are still conscious. Eventually, though, I wake up to a deep quiet. It’s 4 a.m. One or two flashlights are making lonely arcs across the ceiling—somebody is awake—but there’s no giggling. No snoring, even, that I can hear. I find myself feeling rather private and peaceful lying here. On the glass-tiled ceiling, the museum has projected cloudlike patterns that shimmer and swirl; above me, the underbelly of the blue whale is spackled with white, like the Milky Way. I could be at sea.

In truth, our night at the museum turns out not to be the most educational experience we’ve ever had. But it has given us a certain chumminess with a grand institution. We’ve brushed our teeth in its bathrooms! We’ve padded around its exhibition halls in our gym socks! Hey, we’ve slept there!

Margaret Talbot is a staff writer at The New Yorker and a senior fellow at the New America Foundation in Washington, D.C.

Here, four more museums across the country that invite parents and kids to spend the night.

Field Museum, Chicago

Pitch tents, or just unroll sleeping bags, near dioramas of man-eating lions, listen to stories in front of the largest and most complete T. Rex ever found, and wander among the mummies in the darkened ancient Egypt exhibition—if you dare.

1400 S. Lake Shore Dr.; 312/922-9410;; $47 per person; children 6–12; overnights held once or twice a month.

Great Lakes Science Center, Cleveland

At the Great Lakes Adventure camp-in, you can climb aboard a 1920’s steamship docked on Lake Erie (right outside the museum’s back door), test water quality, and examine lake organisms under a microscope.

601 Erieside Ave.; 216/621-2400;; $39 per person; children 6 and up; overnights held three times a year.

International Spy ­Museum, Washington, D.C.

Take on new identities, memorize secret codes, hunt for a mole, and interrogate real spies.

800 F St. NW; 202/393-7798;; $115 per person; children 9–15; overnights held twice a year.

Oregon Museum of Science & Industry, Portland

Bunk aboard the U.S.S. Blueback, the 1960’s U.S. Navy submarine that starred in the movie The Hunt for Red October. As you peer through a periscope and learn to fill ballast tanks and fire torpedoes, you’ll also get a taste of what it was like to have been a crew member living on the ship for months at a stretch.

1945 SE Water Ave.; 800/955-6674;; $55 per person; children grades 3 and up; overnights held every Friday and Saturday throughout the school year.

—Kathryn O’Shea-Evans

Miami Metrozoo, Miami

After the daytime spectators have migrated back to South Beach, Miami Metrozoo comes alive. On your personalized tour of animal enclosures, you can hold bearded dragon lizards, pet a rhino on its horn, and watch nocturnal sloth bears suck up raisins like a vacuum. 1 Zoo Boulevard; 305/251-0400;; from $50 per person; children over six; overnights held several times a year.

Natural History Museum of Los Angeles County, Los Angeles

More than a million fossils have been pulled out of the museum’s La Brea Tar Pits since 1906. At this "Camp Goo" overnight, get a flashlight tour of the bubbly asphalt they came from. 900 Exposition Boulevard; 213/763-3466;; $43 per person; children five and older; overnights held several times a year.

Notebaert Nature Museum, Chicago

Campers have access to all parts of the museum, but chances are you’ll spend most of your time in Butterfly Haven, a 2,700 square-foot greenhouse where all manner of butterflies sprout wings (look for leopard-like Rice Paper butterflies and Cairns Birdwings from Australia, which can be up to nine inches wide). 2430 N. Cannon Drive; 773/755-5100;; $40 per person; children 6-11; overnights held several times a year.

Rubin Museum of Art, New York

Climb "Mt. Everest"—a disguised spiral staircase—at this Himalayan-focused museum with the help of mountaineer Luis Benitez, who’s summated the real thing six times. Each gallery floor serves as a camp with different real-life climbing challenges, like tying knots with mittens on and using supplementary oxygen. 150 West 17th St; 212/620-5000;; $108 per person; children 11-13; overnights held once a year.

San Diego Natural History Museum, San Diego

Wear your craziest-patterned p.j.’s: after you dig for replica dinosaur bones and sleep in the fossil exhibit, Ms. Frizzle—that ginger-haired teacher of Magic Schoolbus fame—will be waking you up for breakfast. 1788 El Prado; 619/232-3821;; from $55 per person; overnights held several times a year.