They don't call it Sodom on the Hudson for nothing.

New York, New York, that libidinous town, has a new museum that celebrates its reputation as the city that never sleeps... alone.

The Museum of Sex opens Saturday with an exhibit titled: "NYC Sex: How New York City Transformed Sex in America." It's an XXX-rated examination of the diverse sexual subcultures that flourished in the city from the early 19th century to the present, encompassing prostitution, S&M; clubs, gay and lesbian bars, the modern porn industry, condom commerce, and the AIDS epidemic.

Four years in the making, MoSex, as it's been dubbed (playing off the Museum of Modern Art moniker MoMA), aspires to lofty heights even if its subject matter gets down and dirty. Founder Daniel Gluck, an artist and former computer entrepreneur, has called his creation,

If You Go What:Museum of Sex. Where: 233 Fifth Ave. at 27th Street, New York. When: The inaugural exhibit, "How New York City Transformed Sex in America," opens Saturday and runs through July 3. Hours:Sunday-Tuesday and Thursday, 10 a.m.-6:30 p.m.; Friday and Saturday, 10 a.m.- 9 p.m. ClosedWednesday. Tickets: $17; must be 18 years old to be admitted. Information:1-866-667-3984; www.museumofsex.com.

which he says is the first of its kind in the United States, the "Smithsonian of sex" - though others see it as a sin-stitution.

"I was referring to the Smithsonian as a respected national institution, a treasure that the country is proud of," he said, toning down the hyperbole. "That's what we want to create here, a national treasure."

His goal, he said, is to bring a scholarly study of sex to a popular audience. While the exhibit is graphic, "it's not just about showing porn films. We're doing something completely different. We're Camille Paglia vs. Larry Flynt," Gluck said, sounding somewhat frantic just days before the opening, with one of the three galleries not yet installed.

Gluck, a self-described suburban husband and dad, is a 34-year-old former Philadelphian who started a software company, Franklin Computing, while a sophomore at the Wharton School. (He also has a bachelor of fine arts degree from the University of Pennsylvania.) He sold the company in the mid-1990s and went to New York, looking to get into real estate.

At dinner with friends, they started talking about the sex museums of Europe, "extremely unserious and cheeky tourist traps," he said.

He thought, "Why couldn't there be a world-class museum of sex?" and set about building one with a former college friend, Alison Maddex, an artist and curator who's no longer involved in the project.

After being turned down by the state for a nonprofit charter, Gluck raised money from private investors. He won't identify them but says the museum bylaws don't permit him to take money from the pornography industry. He also got help from the Kinsey Institute, which lent items from its archives.

But his biggest score was the collection of Ralph Whittington, a retired Library of Congress archivist who amassed what is recognized as the world's largest collection of pornographic literature and film.

"There's a great body of scholarship that has been done over the last generation that has not had a popular audience," Gluck said. "Where else have you seen the history of sex in New York City? Most people don't realize that New York has a sexual history.

"We want to show that free love didn't start in the 1960s, it started in the 1800s."

He is well aware that some people will see the words Museum of Sex and think Museum of Porn. Already, the Catholic League for Religious and Civil Rights has denounced the museum as MoSmut.

William Donahue, the organization's president, said from what he's seen on the museum's Web site, the exhibit "glorifies libertinism."

"I'm no damn prude," Donahue said, "but I do think like a lot of people... that enough is enough."

But Gluck said that, once the museum opens, "people will get that we are not a porn shop. I've worked too hard. If they don't think that way, I don't care."

Though the show does cover porn, there are also the sexual revolution and AIDS and the political mobilization of gays and lesbians and anti-vice crusaders and sex-change pioneer Christine Jorgensen and Mae West and even Wonder Woman.

"She was always tying up foes with her lasso. Something kinky was going on," said executive curator Grady Turner, standing in front of a display of the comic-book superhero, created by a child psychologist, William Marston, with lesbian and sadomasochistic overtones.

The museum is housed in 15,000 square feet in an old building on Fifth Avenue at 27th Street, in, appropriately enough, a former neighborhood of brothels, dance halls and saloons known as the Tenderloin.

Drawing on scholarly research and archival material, the exhibit starts with a display on Helen Jewett, a 23-year-old prostitute whose murder in 1836 exposed the city's sexual underbelly and became its first press-fueled sex scandal.

It follows the zealous anti-vice crusades of a young store clerk named Anthony Comstock, who single-mindedly combatted obscenity in New York. There are the French postcards he collected as proof of New Yorkers' wickedness and his battles with birth-control advocate Margaret Sanger.

The exhibit goes on to show how European immigrants who fled the Nazi threat brought with them not only expressionist art, but sadomasochistic clubs as well.

One of those German immigrants, Julius Schmid, who stuffed sausages for a living, developed a side business making casings into condoms, which he sold as Ramses.

On the more playful side, the exhibit covers the rise of burlesque stars such as Mae West, who was arrested for appearing in a bawdy play early in her career; model Bettie Page; pinup king Irving Klaw; and erotica publisher Sam Roth.

There are elegant examples of homoerotic art, and raw examples of sadomasochism.

Moving into modern times, we catch up with the Happy Hooker, Xaviera Hollander, and porn stars such as Linda Lovelace and Vanessa del Rio, whose experiences in the sex trade varied from degrading to liberating.

Then we come to 1981.

"We're building a crescendo of what is possible in the sexual revolution, and then, boom, it stops," said Turner, who was formerly director of exhibits at the New York Historical Society.

The outbreak of AIDS, the activist group ACTUP, and audio tapes of phone messages as well as letters of an anonymous actor who died from the disease are a sobering conclusion to the story of New York as a sexual frontier.

The exhibit ends with "Safe," showing how AIDS has changed the city's sexual landscape.

Though it isn't the bacchanal it once was, the party is far from over, as seen in "1,001 Nights" - a bank of computers where visitors can read stories of love and lust in the city and add their own.

No museum visit is complete without a stop in the gift shop, and MoSex will have one stocked with books and T-shirts and perhaps some sexual "trinkets," said Turner.

"There are so many sex shops that carry all those things," he said, "that we can't really compete."