Think famous love affairs: Romeo and Juliet. Scott and Zelda. Rush Limbaugh and himself. Roseanne and Tom. Then remember that the first couple ended up dead, the second divorced and depressed, the third rich but fat and alone, and as for the last, rumor has it they turned into hot air blimps in the Macy's Thanksgiving Day parade and were last spotted drifting on the zephyrs above Paramus, N.J.

So for perdurable, passionate, undisappointing relationships, you must turn away from men and women -- who are only human, after all -- to people and places. Think of John and Baltimore.

John Waters, that is, and Baltimore, Maryland -- a perfect meld of sensibilities, possibilities and opportunities; a union that has lasted undiminished through the years. Any marriage should be so lucky. Tom and Roseanne should be so lucky.

Waters has never made a film that hasn't been, first, filmed in Baltimore, and second, imbued with Baltimore values and images. In turn, his films have celebrated the city in a way that no professional sports team or civic PR firm ever could, and in their way put the city on a map it might have otherwise dropped off of.

So it's no surprise that the break-out success of his latest film, "Serial Mom," with its splendid national reviews (it's even showing up in op-ed columns, like Frank Rich's in the New York Times), as well as extremely promising box office, has been cause for nothing short of civic celebration. He's been feted in virtually every publication -- including this one -- by authors -- including myself -- done the talk-show circuit up one side of town and down the other, received warm and glowing endorsement in no less frosty a place than The Sun's own editorial page, and generally had and given a good old time.

Yet in all the hubbub, bub, no one seems to have noticed the following: There's no Baltimore in "Serial Mom."

Not really. Sure, there's an amusingly lunkish portrayal of a Sun reporter-photographer, an abundance of green Towson and N.E. city-suburban glimpses, and a quick, climactic trip to Hammerjack's. But it's all background. What's lacking, for the first time, is a denser sense of Baltimore culture, of Baltimore's uniqueness, of Baltimore as, in Waters' own words, the "Hair Spray Capital of the World."

Of all Waters' films, this one seems the most cheerily generic. And his subject -- a mom so mythically nutso she actually hunts down and kills those who in someway, shape or form, disrespect her family -- really has its roots in no phenomenon that's uniquely Baltimoresque. Rather, "Serial Mom" appears to be sited more generally in the collective unconscious of Waters' own generational experience with the bright, bubbly and perfect moms of '50s TV, those cheerily vapid and relentlessly destructive fables of domestic perfectibility.

But "Serial Mom" could just as easily be set in the suburbs of Baltimore, Ohio, as Baltimore, Md. And yes, there is a Baltimore, Ohio, right outside Columbus, though I doubt it has suburbs.

Though this is far short of apostasy, it's still somewhat unsettling. And, in view of the same, perhaps it's worth considering how Waters and Baltimore came together in the first place, and how perfectly mated they were.

Consider this town in the early '70s, when the just-barely-out-of-his-teens Waters first stepped behind the camera for an attempt to define himself a place in the professional film community: not a happy place.

The Colts had just a few years earlier lost to the Jets in Super Bowl III (the horror, the horror!), the Bullets were about to bail out, the Orioles were just OK, but at that point in history even baseball had yet to ascend to any kind of mythic potency on a national scale (this was before, way before, "Field of Dreams," remember).

An abortive attempt at urban renewal called Charles Center turned large sections of the downtown into a neo-Nuremberg. I used to walk through it on my way to the office trying to figure out where Leni Riefenstahl would place her cameras. No Inner Harbor, no quaint little Fells Point, no restored Federal Hill. Just a big, rotting corpse of a once-great Eastern port city, vaguely affiliated in national reputation with a writer (Mencken) who had died 20 years earlier, and summed up most acutely in a single frame from "Marnie," which managed to include every single Baltimore icon: rowhouse, stoops and, across the street, ships.

Baltimore was about to become Long Beach, Waukegan, or even, God forbid . . . Cleveland.

Along came Waters. Though he couldn't have known it and could never have foreseen it or planned it or possibly even conceptualized it, Waters was about to reinvent the place. The image he created is one no PR firm could have managed and no city committee would have authorized, but it was so unique and resonant it spread quickly from the demimonde to the monde.

Waters had very bad taste and very bad technique, and he penetrated lower-middle class life through the lovably tacky figure of his friend Divine. And in a series of films -- "Multiple Maniacs" and "Mondo Trasho" in 1970, "Pink Flamingos" in 1973, "Female Trouble" in 1975 and "Desperate Living" in 1977 -- he celebrated all that was crass, tacky, disgusting, tasteless and grotesque of this city and its environs. He was Diane Arbus with a sense of humor and without the death wish.

But what you felt more than anything was a kind of secret adoration. He took that which Baltimore was most ashamed of -- its provinciality, its sense of being second best to Washington, -- its enameled beehive syndrome, its industrial flatlands jammed to the hilt with people who went blissfully downy ocean for sand 'n' crabs, hon, every summer -- and enshrined them all.

In so doing, in a very real way, it seems to me, that he liberated Baltimore from shame.

But the truth is that, like Mencken's old Baltimore of hearty German herrenvolk, Waters' Baltimore really no longer exists. In a nearly heroic way, the city reinvented itself in every aspect from image to architecture; it's become gentrified, pacified, blow-dried and self-deified. In some sense, it no longer needs John Waters, just as, in the same sense, John Waters, with his Hollywood contracts and his movie star casts, no longer needs Baltimore.

It says the finest things about both of them that they still hang out together. Waters hasn't dumped the old lady and gone on to acquire a trophy city on his arm; and the city, with its national reputation smeared in all the slick mags, still loves the outlaw with the pencil mustache.