From a distance, they look like abandoned warehouses - row after row of run-down red brick buildings set in a barren field in northern Prince George's County.

Welcome to the Pumpkin Hill Apartments in South Laurel.

People live here, behind the amashed windows and boarded up doors. They live, all but overrun by rats and vandals, in apartments that have gaping holes in the walls. They live in fear of the squatters, whose cooking fires char the floor.

Like many other apartment projects across the country, Pumpkin Hill was built starting in the late 1960s with subsidies from the U.S. Department of Housing and Urban Development.

Pumpkin Hill is not , however, to be confused with public housing. It was built to provide federally subsidized housing for low- and moderate-income families.

The idea was that projects such as these would be a place where a large family could rent a four-bedroom apartment today for about$270 a month - considerably below the going rate in Prince George's County.

Billions of tax dollars were spent nationally - and millions were poured into the Pumpkin Hill Apartments - in pursuit of this Kennedy-Johnson dream of decent, affordable housing for ever American.

In many cases, it worked HUD officials say that nationwide, more than 80 percent of subsidized housing projects are success stories.

But all too often, the dream turned out to be a far cry from the reality.

What millions of tax dollars bought in the case of Pumpkin Hill are apartments that Prince George's County Executive Lawrence J. Hogan recently called "threats to human life."

Pumpkin Hill, moreover, is one of six federally subsidized housing fiascoes in Prince George's County. Almost $35 million - five times the amount the government set out to spend - has been poured into the Pumpkin Hill, Central Gardens, Washington Heights, Baber Village, Nalley and Glenarden apartment projects.

What HUD has to show for that $35 million today are six ugly and dangerous suburban slums.

The big losers - besides the tax payers - are the very people that the 2,140 apartment units were built to help.

Low- and moderate-income families in Prince George's - who in some cases could only watch helplessly as their homes were deliberately condemned as a way of herding them into the projects - have suffered through their swift decline. Someof these families are worse off than they were before.

In all too many cases, the winners have turned out to be the private developers who snapped up federal loans and subsidies designed to encourage construction of these apartments. Some of them, with little or no investment, have walked away from these projects millions of dollars richer.

How could this happen?

In theory, the projects and their developers were subject to volumes of federal regulations and county housing codes, enforced by ranks of well-paid bureaucrats and inspectors.

In fact, government specialists must take a major share of the blame for the waste of tens of millions of dollars in Price George's alone. A Washington Post investigation showed that government agencies allowed or forced developers to build poorly designed buildings in impractical locations, failed to report or detect decay and permitted substandard buildings and grounds to exist that way of years

Most incredibly, HUD officals confes they have no real ide how much government money has gone into these six projects-or any one of them, for that matter. No such accounting has ever been made.

The figures used in this series were compiled by The Washington Post from government records.

But while HUD may not know exactly what it has poured into these slums thus far, officials nevertheless are making plans to throw in as much as $5 million more to bail them out.

For the government, officials insist, does not regard the two federal programs under which the six projects were built as failures.

"This program has been labeled a failure, but that is really unfair," says Marilyn Melkonian, HUD's assistant secretary for housing. "There have been problems with the program, but we are making dramatic changes. Our policy has been to preserve as much of this housing as possible. We consider it an asset."

HUD officials note that the six projects discussed in this series represent only 40 percent of the apartments built in Prince George's County under the two federal housing programs. Many of the other projects, federal and county housing officials say, have managed to operate adequately.

But conditions in the six troubled projects could hardly be worse.

The most spectacular failure has been Baber Village, off Central Avenue in a low-income area of Seat Pleasant. Vacant for more than two years, its 200 units are boarded up, surrounded by wire fences and patrolled by guards.

"It's ghostly remains," wrote one county housing inspector, "are almost indescribable."

Stained brick walls broken by plywood squares, create the impression that a war has recently reged here. Inside, walls, floors and appliances have been reduced to piles of rubble.

Already demolished in part, Baber Village has been the subject of a bitter year-long fight between HUD and Prince George's over what to do with the ruins. The county wants the existing apartments leveled. HUD, in accordance with its national policy of salvaging housing, wants to rehabilitate them, at an estimated cost of two to three times the original $2.9 million invesment.

Already, HUD has spent nearly $4.9 million on the project in subsidies, repairs, maintenance and loans that were never repaid.

Across the street from the barbed wire of Baber Village is Central Gardens, where HUD has lost through default most of a $1.3 million loan.

The half-dozen brick buildings here have no main doors. Instead, ill-fitting splintered and stained plywood boards only partially block the entrances. Many basement rooms are vacant. They flood when it rains. Through their windows one can see warped linoleum, crushed wooden furniture and piles of broken glass.

Central Gardens has been controlled by HUD for nearly a year. Yet the conditions there, housing inspectors say, have grown worse. In early July, county officials condemned the project and said they would evict the families in its 94 apartments on Sept. 1 unless severe erosion problems around the buildings were corrected.

The erosion has left deep pits in the ground in front of several buildings, exposing rusted drainage pipes with jagged edges. Until recently, tenants had to pass through the trenches to reach one building; now, they can use a narrow plywood bridge. When it rains, the pits and trenches become rivers.

About a mile northeast of Central Gardens and Baber Village, in what was once the Prince George's Model Cities area, two more projects stand side by side. Washington Heights and the Nalley Apartments, government records show, have cost federal tax-payers about $3.6 million.

The buildings of both projects are perched on relatively flat portions of a snakelike ridge that runs down a steep hill. Many apartments have been wedged against the hill, and torrents of water pour into basement apartments after a rainstorm.

On one side of the Nalley Apartments, the hill drops sharply into a brush-filled gulley, which is littered with rusted refrigerators, steel drums, bicycle parts and other debris.

Boarded apartments, sometimes decorated with spray paint, are everywhere on the hill. And violations of the county's housing code, recently cited by inspectors at Nalley, were typical of conditions at all the projects, county officials say. They included: holes in foundations walls; hallway doors that were cracked, missing or broken; smashed fire alarms; broken glass panes; broken lights in most hallways; piles of trash in most furnace rooms, and exposed electrical wiring in hallways.

Many of these were cited in April, 1978, county records show. By last March, they were still uncorrected.

About a mile to the northeast is "slum valley." This is what tenants call the white brick Glenarden Apartments. Here, too, plywood boarding and broken windows are common.

The glass often winds up strewn over the parking lot. And crime in the project is so bad, tenants say, that they are afraid to walk from one end to the other at night. The county recently ordered that all buildings at Glenarden with less than 50 percent occupancy be vacated by Sept. 1, because, county officials say, they are safety and health hazards.

In part because the project's original owners defaulted on their loans and deeded the property back to the government, the project has been particularly expensive for HUD: it has cost about $13 million over 11 years for fewer than 600 units.

Finally, eight miles farther north in south Laurel, there is Pumpkin Hill. Its 825 units have also cost the government nearly $13 million over the last 11 years. In February, 39 of the 69 buildings were condemned after county housing inspectors found them unfit or unsafe for human habitation.

The project's owners have deeded most of it back to HUD after falling $1 million behind in loan payments, and HUD has spent nearly $1 million to pay bills and make repairs necessary to prevent the county from clearing and razing the project.

Still, conditions have not improved for many since the condemnation. Dozens of families at Pumpkin Hill have refused to pay rent for several months, protesting what they say are intolerable invasions by rats and cutoffs of heat and water.

"Somee people feel the conditions have improved here," says Maria Hill, the tenants' association president. "But it's still pretty much a slum." (NEXT: The Tenants) CAPTION: Picture 1, Plywood covers windows of Baher Village apartments in Seat Pleasant. By Gerald Martineau - The Washington Post; Picture 2, Baber Village's "ghostly remains," wrote one Prince George's housing inspector, "are almost indescribable." The complex has been vacant for more than 2 years; Picture 3, Vandals ravage Baber Village units, taking kitchen and bathroom fixtures. Photos by Gerald Martineau - The Washington Post