THEY CONCEIVED AND DESIGNED the Rockville Mall fifteen years ago according to the tail-finned 1950s blueprint of the American Dream, but something went terribly wrong. It almost reminds you of that major in Vietnam who stood watching the velvety black napalm clouds coming off some ruins, turned to a correspondent and said: "We had to destroy the town in order to save it."

It all made sense to the major and for a minute it made sense to the correspondent. Of course! How clean. How precise. A fresh start for everybody.

Then something clicked in the correspondent's mind. He put the quote on the wire and suddenly the rest of the world saw and understood exactly what had gone wrong in Vietnam. Wait a minute, men! You don't put a whole country under Urban Renewal.

But by then it was too late. The whole merry-go-round of . . . more is better . . . had taken off into the sky in a whirl of fairly dust.

In the late 1950s and early '60s, shopping malls were to the consumer side of the American Dream what "Making the World Safe for Democracy" was to its foreign policy. It was an axion of the Dream that shopping malls would stimulate business, just as it was an axion that if Vietnam fell to the Communists, the whole shooting match would be lost.

THere are chunks of flotsam all over the country (but especially in California) from when the incredible Horatio Alger power of the Dream pushed things over the edge. Some are monumental, like Howard Highes' giant $20 million plywood plane that he flew less than a mile and then mothballed in a $3 million-a-year hangar in Long Beach, California. Some are individuals like Lucille Miller, whose vision of the Californian good life was so powerful she murdered her husband for $120,000 in insurance and a better-looking man. Some are grotesque, like the $1.4 million dream house, the Governor's Mansion that Ronald Reagan built for himself in Sacramento, California, and which now lies vacant because Jerry Brown prefers a $275-per-month apartment. Many of them are documented in a book of essays called Slouching Toward Bethlem, by Joan Didion, a Los Anglels writer. Didion is the premier purvevor of the dark side of the American Dream. It's obvious that once upon a time, before she went through whatever it was that caused her . . . estrangement . . . she was in love with it. Ex-lovers make wistful but deadly accurate critics.

There has always been a special place in Didion's heart for shopping malls. As she wrote once "they are toy garden cities in which no one lives but everyone consumes, profound equalizers, the perfect fusion of the profit motive and the egalitarian ideal." Didion herself, caught up in that "perculiar and visionary time years after World War II," once took a course in shopping center design, figuring she could cash in one the Dream. Now, with the Fifties fading into accident history, she sees even the successful ones as "pyramids to the boom years."

The Rockville Mall is a special case, though; a kind of fatally flawed pyramid, if you can imagine that. I'd love to show it to Didion, or just follow her through it some rainy winter afternoon. She's such a connoisseur of misadventure it would probably be like watching an expert wine-taster trying a small new vineyard, that just might turn out to be a little gem. And she wouldn't have to worry about crowds.

This mall is very hard to find. It's low as a barracks or a prison, only one real floor to it (the three others are underground parking, although the lowest, like a coal mine after a disaster, has been sealed off). The outside signs are small and unlighted and do not point the way. The maze of approach roads to the few entrances are full of dead ends and doglegs. The mall's main pedestrian entrance faces on an urban renewal desert; the inscrutable brick rear is what you see from the city streets. Although it's medium-sized, as malls go, its profile is so low that some residents of the area say they've been driving by its for years without realizing it's there.

You come up into the mall from underground on escalators winding around two huge concrete shafts. On the entrances to the parking levels, and mirrored endlessly on each underground pillar are color-coded fruits, in a complicated system to help trace where your cars lies buried. Trying to recall whether it was the purple grapes on Level Two or the yellow lemons on Level One, you begin to get a whiff of the mall's atmosphere.Are you being made fun of? A consumer prince?

The overall effect, in fact, is almost a kind of perverse anti-consumerism, to which the frustrated consumers who finally make it inside have responded with grafitti and vandalism. A month ago the men's room looked like a consumer had finally run completely amok: he had tied into the stall partitions until they looked like potato chips. He'd knocked tiles out of the walls, leaving four-by-six-inch holes. Leaping high into the air with his fist outstretched, he'd punched panels out of the ceiling. Finally, seeing his desperate face staring back at him from the one remaining unbroken thing - the mirror - he'd taken his shoe off and battered it to tiny silvers with the heels. By God, he'd never shop here again.

This mall was originally planned as a giant dumbbell, with two department stores for weights on each end and the arcade with smaller stores along it for the bar connecting them. But one of the department stores, Lansburgh's closed for good in 1973, a year after the mall opened, and the other was never even built.

What you see most of are yellow and green plywood panels that wall off the vacant store space (about thirty per cent of the entire 380,000 square feet). There's room for sixty stores, but right now there are only thirty-three (down from forty-two in 1975): four medium-rent women's clothing stores, three men's shop, a variety store, a furniture store, a finance company, a bank, a music store, a record store, a key-making booth, a bookshop, three shoe shops, a handicraft store, art gallery, two jewelry store, movie theater, a gift and greeting cards shop, Japanese curio boutique, photography studio, frame shop, three fast food places, two restaurants and an ice-cream parlor. There's no drug store.

The puckish designers of this mall have done lip service, at least, to the shopping center tradition of having plants growing in bins down the center of the arcade. They have the bins, but not the plants. The benches around the empty bins are in a similiar puckish vein. They are narrow, concrete backed, close together and bolt upright. They go well with the little signs on all the entrances: no loitering. No one does.

There are a few people to loiter maybe twenty or thirty clicking their heels emptily on the brick floors in the middle of a pre-Christmas afternoon.

There is a Santa, but he does a lot of sitting and staring. "Let's look on the bright side of things," says a saleslady in a deserted music store. "It's nice and quiet in here." Gift shop owner Murray Brill says he's not going to move because Montgomery Mall is full and the new White Flint mall is overbooked for his kind of specialty. David Lee, who delicately calls his mall Express Restaurant branch a "hidden shell," recently settled out of court for a rent reduction, so he'll stay.

Rick Gross, 48, who owned two Washington "head" stores selling counter-culture posters, frames, gift and other paraphernalia, was one of the merchants courted by the new mall in 1972.As he tells it now, the Rockville experience came close to literally causing his death .

"This thing was very ironic, you understand," he remembers, "because Rockville is in the heart of the richest county in the country. That's why we went in. That's why everybody went it. It sounded so good. They had an impressive list of stores lined up, not dummies, not Mickey Mouse. Two department stores. It was going to be a regional mall, drawing its customers from a larger area than just Rockville. Boy, did we get buffaloed."

When the mall opened in early 1972, Gross' third Generation Gap was among the sixteen original stores. Things went as well as could be expected until Lansburgh's folded about a year later. Lit Brothers, a Philadelphia-baed mail order outfit, tried a mall outlet in the vacant space but it closed after six months.

"From then on, every time the place tried to get on its feet," said Gross, "something would happen." Vandalism and mugging in the underground parking got into the papers. Plans for two other area shopping malss were announced, putting even more of a squeeze on Rockville.

Gross watched the mall clientele dwindling down to the lunchtime locals and his own books turning redder by the minute. His Landmark Mall outlet in Alexandria, measured in profit per square foot, was doing almost three times as well. He began scraping for his rent to the mall.

"I got a lawyer to explain to the interested merchants what our alternatives were. If we could have gotten together in a rent escrow or a claim that the situation was misrepresented to us, we might have gotten relief. But they didn't want to spring for it. Most of the stores in there are chains and the managers could not make the decisions."

By the fall of 1974, Gross had let all his help go and was running the store himself. He was spending so much time in Rockville his other stores were beginning to suffer. The huge Christmas inventory he'd laid in was giving him cold sweats at night. He was putting in 72-hour weeks tyring to move it, working "every ounce of blood in my body." And the more he worked, the more he began to realize he'd made a terrible mistake.

That's when he had his heart attack. A year later he declared his entire company, all three-outlets, bankrupt. The whole thing reminded him of a piece of fruit, going slowly rotten, collapsing in on itself.

"What am I doing now?" Gross' laugh is a quick intake of breath, completely mirthless. "Just say I'm trying to pick up the pieces. Trying to make a new start. I went in there on the crest of the wave. Times were good. It was an absolute gold mine in the richest county in the country. And it didn't draws . . ."

Although the county and city have helped the mall make ends meet by leasing office space, recently the county police announced their large underground quarters were "inappropriate" and they hope to leave when their lease is up this summer. Since they moved in two years ago, police personnel have complained about lack of ventilation (causing nausea and perennial tiredness in at least one worker, they say), faulty air conditioning and heating, live roaches blowing out of ventilation ducts, water coming through ceilings, and overflowing toilets. In one of the subterranean cubicles someone has posted a mock condemation notice : "THESE PREMISES ARE CONDEMED AS UNFIT FOR HUMAN HABITATION."

Statistics for this $14 million mall paint a picture almost as gray as its concrete superstructure:

- Its operators are losing about $300,000 a year because of the thirty per cent vacancy rate.

- Debt retirement on the $7.5-million city-owned underground parking (ninety per cent of which is eventually supposed to be carried by retail profits from the mall's stores) is costing the citizens of Rockville seven cents on every tax dollar.

- In 1974 alone the mall owners took resident merchants to court twenty-three times, pressing for $160,000 in unpaid rent. At least six stores filed countersuits, claiming the mall lessors lured them in with promises that the mall would be substantially leased and would include at least two major department stores.

I have a feeling that if Joan Didion ever designed her own mall it would be similiar to Rockville's, with some fatal gap of logic that would end up purveying the dark side even more effectively than her essays. And at last, when the project had completely collapsed, all the stores had closed and the developers had declared bankruptcy, Didion would have the mall all to herself and she could stroll in the cool twilight from window to empty window, the last survivor of the Great American Holocaust she has always predicted, maybe fixing herself a sandwich with some abandoned pumpernickel and salami.

Mayor William Hanna, like a man who has inherited a disease, obviously wishes the mall would vanish in the night. "I avoid it like the plague," he says. "I've never heard anybody in my life say they liked malls. Even the successful malls are cold, impersonal communities of money changers. Their personality is zero."

He smiles ruefully. "Financially, the rest of the city awards in the past and we're a finalist for one this year. The mall is our only problem."

Well, how id it happen?

Whereas: Rockville Center in the late Fifties needed "revitalizing."

Whereas: Exurban shopping centers and malls were the most vital new concept of retailing ever to hit the American business landscape.

Therefore: Replace the central business district with a shopping mall.

Here seems to be the fatal gap of logic. The giants of mall buildings, such as Eddie DeBartolo, almost always built on privately owned undeveloped land with perfect excess, never downtown. "I wouldn't put a penny downtown," he said once. Certainly, there have been some malls built in downtown locations, but these have usually been in larger cities, as an adjunct to the original retail district. The Rockville plan was very possible unique in that it envisioned replacing virtually all the downtown retail district with a mall. It took the logic right down to the bitter end.

What finally happened, of course, was that they destroyed Rockville center in order to save it.

Frank Ecker, the mayor in those days, is now the public advocate for Montgomery County and if he sticks his head out his offive window he can see the mall. Like almost every city official involved in its contruction, he loves to talk about what he would have done differently.

"Getting into Urban Renewal was our big mistake," Ecker says now. "It took much time. You need two appraisals to buy any property. Everything has to be approved by the HUD regional office in Philadephia. You often have to go to condemnation court to buy. We figured the whole process would take about two years but it ended up taking five. Would you believe we had to go through 247 different steps?"

Under Urban Renewal, they leveled about 100 small lots and "relocated" 165 businesses. In their place, beside the mall, they planned a 422-unit apartment complex, a new county courthouse and a new county office building. The courthouse and office building have yet to be built.

One result of the delay was that the sleek Montgomery Mall opened four years ahead of Rockville, with all the major stores that Rockville lacked. Another was that many of the original downtown businesses, which might have provided the backbone of the new mall, could not wait for its completion and moved elsewhere. Or just folded.

The local tavern, Roy's Place, moved to Gaithersburg where it has now become almost an institution and might easily draw more daily customers than the entire Rockville Mall complex. The last business left before the levelling, the original Roy's had a thick and hectic Klondike cachet: old posters, nine Taffany lamps, great food and more customers than it could handle. It was a little funkly for your average shopping mall.

"The people who were being moved out were supposed to have first choice at locations in the new mall," Roy Passin remembers now. "So we went to talk to the lessors. The original leasing guy was an arrogant, cocky young guy from New York hustling chain stores, very up on all the trends. He offered us a tiny space in the middle of the arcade and told us, 'Look, forget your sandwiches. You're going to have to run a steak and chop place here.' So Roy got an SBA loan, built the Gaithesburg place and says that "probably the best thing that ever happened to us was getting booted out of Rockville."

The former mayor blames HUD. County officials tend to blame the city planners for "trying to ordain a regional shopping mall" with the hazy philosophy that "if you put one up you can't go wrong," and not bothering to lay the proper groundwork. That included, some county people said, selecting a New York developer who had built a shopping center before.

To which the city planners reply that they selected the New York firm on the basis of its "unique" design, and it was the firm's own failure to follow through and lock in two department stores that has caused the catastrophe. Now, they say, the New York firm seems to have written off the whole thing. "They haven't put a dime into this place for months," said Douglas Horne, the city's director of community development and housing assistance. "It's known all up and down the East Coast as a turkey."

At the end of this triple play of recriminations, mall manager Argerie Hoty throws the ball back to the city. "Marketing studies at the time advised against the mall," she says. "The city simply ignored them. They knew about plans to build Montgomery Mall, too, and they ignored that." (The city denies both points.)

N. Anthony Rolfe, spokesman for the New York group that owns the mall, refuses to comment at all.

Right now, there's a kind of resigned, water-treading feeling at the mall. The stores that are left have mostly negotiated rent reductions so they can survive in a kind of suspended animation. Local speculation has it that Sulzberger-Rolfe, Inc., is using the whole thing as a tax write-off and has no immediate plans to declare bankruptcy. Mayor Hanna, who admits "we couldn't tear the thing down if we wanted to because of all the federal money involved," has negotiated several times with the county to have it lease more office space. Or perhaps even to turn the entire mall into a county office building instead of putting up a new one as called for in the orginal Urban Renewal plan. "It would save millions of dollars," Hanna says, "but the county executive seems quite negative on that." There is talk of getting "specialty shops" aimed at local trade to move into the mall. After all the new office buildings, (for which ground breaking is scheduled two years from now) are expected to add another 3,000 potential consumers to the lunchtime crowd.

Something will turn up, is the feeling. The Dream, reduced and withered as it might be, dies hard.