"My dearest beloved," the voice-over starts, as a presumably 18th-century fellow writes impassionedly in the television commercial. "How I long to be with you, to see your radiant smile. Please journey to Philadelphia, where we will be at liberty to meet this Monday, at Independence Hall, as the clock strikes 6."

In the next scene, the man in period attire waits with flowers. An attractive girl flirts with him as she walks by. Then, another man sneaks up behind him and they walk away together.

"Come to Philadelphia," the voice-over then says. "Get your history straight. And your nightlife gay."

As Congress considers an amendment to the Constitution to ban same-sex marriage, the city where the document was drafted is inviting gay couples to visit. The Greater Philadelphia Tourism Marketing Corp. (GPTMC) is the first government-supported tourism agency to attempt to attract gay tourists via television. The above ad, in part developed by Comcast Corp., is to air this summer on Comcast cable systems along the East Coast, including the Washington area, and on such networks as VH1, Bravo, Comedy Central and MTV.

It is all part of a multimillion-dollar campaign by the GPTMC to bring gay visitors to Philadelphia, whom the agency has found to be avid travelers and to spend more money than straight tourists.

"No one would call Philadelphia the number one gay city, but if they can show they are gay-friendly, they will reap a lot of rewards," said Jeffrey Marsh, the director of advertising for Orbitz, an online travel service that has its own gay-oriented travel marketing site. "And they are committed. The gay community doesn't want to see some short-term campaign, but an ongoing commitment. Philadelphia has a multiyear plan, and I applaud them for it."

Jeff Guaracino, who runs the gay initiative for the GPTMC, said Philadelphia's official push for the gay travel market is good business. He points to research his group commissioned showing that gay travelers spend $54 billion a year, and that they spend $500 per two-day domestic trip, traveling on average three or four times a year.

"We then found out that aside from typically gay places, like Provincetown and Palm Springs, no big destination was making a large push," he said. "We wanted to be the first."

Philadelphia has a big advantage in gay-tourism marketing in that its prime mainstream tourist asset -- the historic area surrounding Independence Hall -- is contiguous to the upscale gay nightlife and shopping district, as well as the city's arts center. A 10-minute walk from the Liberty Bell brings visitors through tree-shaded and brownstone-lined streets dotted with gay and mainstream bars and restaurants. A few blocks away are several theaters and the new Kimmel Center for the Performing Arts -- home of the Philadelphia Orchestra.

In this area is the Alexander Inn, which innkeeper John Cochie claims is Philadelphia's only gay-owned-and-operated bed-and-breakfast. Cochie came to Philadelphia 15 years ago and decided to stay when he felt it was gay-tolerant, and often gay-friendly. Two years ago, though, he decided he really wanted it to also be welcoming to gay travelers, and he gathered together some gay business owners to form the Philadelphia Gay Tourism Caucus.

"I went on the Internet and saw that Philadelphia was not on the top 20 list of places gay people wanted to vacation, which wasn't a surprise," Cochie said. "But then it also wasn't on the top 20 places they wanted to live and work, and I knew that shouldn't be.

Cochie's group grew from 10 gay business folks at his first meeting to more than 100 gay and straight businesses now. It helped induce the GPTMC to publish print ads in gay-oriented publications -- one showed Betsy Ross sewing a rainbow flag -- and then having the organization start a gay section on its tourism Web site (www.gophila.com/gay).

Now there is a 32-page full-color gay visitors' guide to Philadelphia that can be ordered from the Web site and a list of 13 hotels offering the Philadelphia Freedom package, which offers hotel stays, a continental breakfast, and a gay-friendly welcome packet with some discounts and specials at gay-friendly businesses.

"We have 13 hotels signed up, from small ones to places like the Sheraton Rittenhouse," Cochie said. "We've offered sensitivity training if businesses want it, but so many have been cooperative, it has been a pleasure doing this."

Tourism Montreal, that city's official tourist agency, has been targeting gay tourists for a decade, said spokesman Yves Pelletier, who said Montreal has had little competition among official agencies until Philadelphia's new push. (Washington has, in fact, done some print advertising in gay-oriented publications.)

Montreal, he said, targets getting big events that would attract large amounts of gay tourists at once. It has a huge gay arts festival every August and has hosted the International Gay and Lesbian Travel Association convention. It will be the host of the first World Out Games in 2006, with the expectation of 16,000 competitors, in addition to fans, for a week of Olympic-style events.

"We in Montreal think we nurture differences, so it was natural to market travel to gay people," he said. "Gay people, like everyone else, don't want to be looked like they are from outer space. If you can push them to gay-friendly places, they will appreciate it and come back again and again."

Though they have large gay populations, San Francisco and New York have not embarked on tourism campaigns. "I can only guess that San Francisco just doesn't think it needs something like that," said Michael Wilke, the founder of Commercial Closet, which monitors advertising toward -- and against -- gay audiences.

"What Philadelphia is doing is unique, in that it is going into mainstream media and television and making a series of partnerships in its own community to make it permanent," Wilke said. "I think the gay community is tiring of being herded to places like Provincetown and Key West and wants to go to places like Philadelphia, if they can be shown they will be welcome.

"If the official tourist agency does this, it mutes the right wing from seeing grounds for objections," he said. "You don't want to be cynical. Sure, around this is that gay people have money. But they had money before, too, and now, at least in Philadelphia, they know the local people there are welcoming them to spend it comfortably."

A new TV ad from Philadelphia's tourism marketers says: "Come to Philadelphia. Get your history straight. And your nightlife gay."