As midnight approached, a trail of men filtered into the movie theater to watch X-rated gay movies and eye each other in a warren of dimly lit lounges. A few steps up the street, a half-dozen men danced nude for a barroom crowd, while next door a female impersonator known as Ella Fitzgerald sashayed down a staircase in a brunet wig and a glittering blue-and-red gown.

"What have you done today to make you feel proud?" the impersonator lip-synced to a booming soundtrack as the audience roared and men lingered at the darkened edges of the dance floor, waiting to hand him dollar bills.

For three decades, gay men seeking sexually oriented entertainment have traveled to a neighborhood of warehouses and industrial plants a mile south of the U.S. Capitol and unknown to most of Washington. Established before the emergence of AIDS, the block of O Street SE is a kind of 24-hour mini-mall of prurience, where some members of the gay community buy X-rated magazines, videos and sexual paraphernalia, watch nude dancing, visit the city's longest-surviving bathhouse or meet other men, at times for sex.

But with the city planning to build a baseball stadium for the Washington Nationals on land that includes the O Street block, just off South Capitol Street, the strip is being pushed to extinction. D.C. officials have notified property owners that the city will make offers for their parcels, possibly by next month, and that it intends to force out those who don't move by year's end. The owners of the half-dozen establishments, as well as gay activists, want the city to help them relocate.

"These are legitimate, legal businesses, and in one of the capital cities in the world, it would be outrageous if we couldn't find a place for them to open once they're forced to close in their current locations," said Peter Rosenstein of the Mayor's Gay, Lesbian, Bisexual and Transgender Executive Advisory Committee. "They're not closing because no one is going there. They're being forced to close because the city is taking over their land."

More than a generation ago, adult entertainment flourished along Ninth and 14th streets NW, which were crowded with bars and bookstores that peddled pornography, steam baths and hustlers. As redevelopment transformed those areas, a new scene was born on O Street, eventually becoming part of gay Washington and now known nationally as one of the only strips where male dancers perform nude.

"It was our own piece of Washington," said Larry Stansbury, executive director of Brother, Help Thyself Inc., a gay charity that supplies condoms to several of the businesses.

Gay activists and the O Street proprietors acknowledge that finding a new location for the strip will be difficult, if not because of zoning restrictions, then because of real estate pressures and resistance from civic groups.

"I'm aware of the political tone of the city and the amount of opposition there is to these places," said Richard Rosendall of the Gay and Lesbian Activists Alliance. "But I don't think we should allow the bluenoses and the busybodies and the not-in-my-back-yarders to win without a fight."

That view is not universal. At an April meeting on the strip at Ziegfeld's, which has featured drag shows since the 1980s, Christopher Dyer, a gay activist and an elected advisory neighborhood commissioner in the Logan Circle area, said that he is sympathetic to the clubs' plight but that gays face more pressing issues, such as securing funding for HIV prevention.

"I have trouble expending a lot of political will on this," he told a crowd that included seven of the D.C. Council's 13 members.

Beginning in the 1970s, clubs catering to gay men and lesbians started moving into the area, in part because of relatively cheap rents. Club Washington, the gay bathhouse, opened in the early 1970s, taking over a former wholesale grocery warehouse. It was followed by two strip clubs, now Heat and Secrets, as well as Ziegfeld's. In the late 1970s, the Follies movie theater and Glorious Health and Amusement, an arcade and theater, moved into a building that housed a carpet cleaning company.

Frank Kameny, 79, a longtime gay activist, said a perception existed that police would ignore gay-oriented businesses if they opened in areas removed from downtown. "It became an out-of-sight, out-of-mind kind of thing," he said.

At times, the businesses have found themselves in the limelight. In 1977, nine patrons died in a fire at the movie theater, then on L Street SE. Twenty years later, a police lieutenant was arrested for attempting to extort patrons. Mostly, though, the businesses have remained in the shadows, near an asphalt plant and sewage pumping station and across from a Metrobus parking garage.

"They exist in their own world down there, and they don't bother anyone," said council member Sharon Ambrose (D) of Ward 6, which includes O Street.

The isolation has not been without inconveniences. Marty Crowetz, 53, a former part-owner of Follies and now a contract engineer with the U.S. Department of Veterans Affairs, said that in the early years, he bought a snowplow because D.C. workers did not show up to clear the street. On many nights, he said, he and other gay ex-Marines -- GEMs, they called themselves -- patrolled the neighborhood, sometimes with a German shepherd, to ensure patrons' safety.

But, he said, at a time when homosexuality was taboo in many quarters, the street's remoteness also allowed people to visit without fear of being stigmatized. "It was freedom for me," he said. "I didn't have to hide. It was my getaway."

The strip's reputation has spread in recent years, now that cities such as New York and San Francisco, with new regulations restricting adult entertainment, no longer have establishments that serve alcohol and feature nude dancing.

On O Street on a recent Saturday night, a crowd filled Secrets, where six nude male dancers gyrated while gay pornography played overhead on more than a half-dozen television screens.

Roland Dunbrack, 41, a biochemist from Philadelphia, said he looks forward to trips to the District for the chance to spend a night on the strip.

"Washington, D.C., is one of the few cities where you still see full nudity," he said between sips of vodka and cranberry juice. Dunbrack said O Street is "part of an adult urban culture. We're not all perfectly well-behaved people. We like to have fun. If we get rid of this, we have a straitjacketed culture."

George Phillips, general manager of Club Washington, described it as a 24-hour health club, showing a workout room with a rowing machine and weights, all unused at the time. The club features 30 cubicles, each furnished with a locker and a mat large enough for a person to lie on, as well as lounges where a few men wearing towels watched an X-rated video. Phillips said he was aware that club members engage in sex in the bathhouse but said the club does not condone it. "What they do behind closed doors is up to them," he said.

Sgt. Brett Parson, commanding officer of the D.C. police gay and lesbian liaison unit, said sexual activity in the establishments is not criminal if the participants are consenting adults and "their acts are not infringing on public space."

At Follies, also open round-the-clock, patrons walked between the main theater and a loop of darkened lounges with wooden booths large enough to hold two people. The theater's overnight ticket taker, who agreed to talk if he was identified only by his first name, Dave, said he was unaware of what transpires in the theater and the lounges. "I can't see through walls; I don't see what people do," said Dave, 65, standing across from a framed poster that read, "A Good Partner Keeps You Covered, Condoms Available."

Leaning on a nearby counter, Al Ritter, 54, a lab scientist for the Maryland Department of Health, said O Street has grown more important to him since the strip club he frequented in Baltimore closed.

"This is our social life. The feeling is, if it goes here, I don't know what we'll do," he said, adding that talk of the new baseball stadium now pervades every visit. "It's almost like we're under sentence here, like we're awaiting execution."

Downstairs is Glorious Health and Amusement, whose proprietor, Robert Siegel, owns 13 properties in the neighborhood, including those occupied by Heat, Secrets, Ziegfeld's and Follies. Siegel, the area's elected advisory neighborhood commissioner, has sued to block the city from seizing the land.

On a recent night at his arcade, where employees sell sexual aids and pornography and candy from behind security glass, patrons paid $17 to enter a suite of low-lighted backrooms that include a 12-seat theater where an X-rated movie was playing. Most of the place was occupied by banks of wooden booths, which patrons circled, sometimes going inside.

In an interview in his windowless office, furnished with a pullout couch on which he sometimes sleeps, a refrigerator and a wall of security monitors, Siegel described his establishment as a "walking club," explaining that the walkways form a circuit, and the booths are "a place to change clothes." He later acknowledged that patrons "occasionally" have sexual encounters. He was reluctant to discuss the subject, he said, because it could make it difficult to relocate. "I do not want you to put a dark cloud over my business and tenants," he said.

The businesses would need city approval to move downtown. To relocate to certain industrial neighborhoods, the nude dancing establishments would need permission to transfer liquor licenses.

Because the city plans to take the land, it is legally obligated to help the businesses relocate if they seek assistance. Carol Mitten, director of the D.C. Office of Property Management, said her staff has identified a number of industrial areas as potential sites but said it would be "a serious challenge" to relocate them together because of the lack of commercial properties.

Whatever transpires, O Street's owners and patrons know their world is at risk. At Ziegfeld's, Donnell Robinson climbed the stairs to his dressing room, where he keeps a closet filled with wigs, high heels and all the rest of the accoutrements that help transform him into Ella Fitzgerald.

"It's a little devastating," he said of the prospect of the clubs shutting down, as he applied makeup and smoked a cigarette. "But as I tell my friends, I have no regrets. I've spent 25 years here. Come what may."

Drag shows are a mainstay at Ziegfeld's, one of the O Street businesses that will have to move to make way for the new baseball stadium.