LAS VEGAS — They blow up aging casinos in this town. Now, some are wondering what to do about yesterday's desert dream homes.

Take the foreclosed million-dollar house realty agent Michael Antos recently showed. Please.

To the untrained eye, the four-bedroom, five-bath retreat might appear top-drawer, shimmering with granite and marble throughout, with posh touches like a pool with a sandy beach entry.

But Antos pointed out that the house was showing its age. After all, it was built in 2000. In Vegas, that makes it as dated as a coin-operated slot machine.

The chandelier? Plastic. The granite surrounding the upstairs bathtub is tile, not slab. And those polished travertine tiles in the entryway might look luxurious, but at 12 inches by 12 inches, they just won't cut it today.

"Now you've gotta have at least 20 by 20 to sell something at this price," Antos explained.

The housing slump has fattened the inventory of unsold homes throughout the country. But there's another twist to the story here — a glut of glitzy homes.

About 1,000 houses are listed for sale in Las Vegas for $1 million or higher, more than 600 of them built since 2004. But unless they've been built in the past year or two, the properties are considered out of date — making them all that more difficult to sell, real estate agents say.

In most of the country, prized neighborhoods become even more desired over time (think Beverly Hills, Calif., or Greenwich, Conn.). But Las Vegas isn't about stately trees, old lawns and older money, said Gene Moehring, chairman of the University of Nevada, Las Vegas history department and a specialist in urban history.

"In Vegas, new is the most important thing," Moehring said.

And building homes is relatively easy — Las Vegas is surrounded by desert land available for development, so there's always room to build a more-opulent golf course community across town from the last hot spot (concerns about the region's limited water resources has yet to stem the building boom).

The new homes often don't cost much more than the older ones, at least to buyers at the top end, for whom a couple hundred grand here and there won't make or break a deal, said veteran Las Vegas real estate broker Michelle Sterling.

"Once you get into the market over $2.5 million, a lot of people just prefer to build their own," she said.

One developer, Christopher Homes, recently opened a neighborhood of homes in the hills west of the Strip selling for $1.7 million to $3 million. Several of the houses so far have sold to residents of adjoining neighborhoods who lived in their houses for less than five years, including homes built by the same developer, said Erika Geiser, the company's vice president.

"They feel their residence is obsolete," she said. "They're looking for something more innovative, more cutting-edge."

Michael Lemoine, an architect who specializes in custom houses for the wealthy, says he has clients who build houses as often as some people buy cars.

"New neighborhoods pop up that become the place where these people want to live," he said. "They move from one to another because they want to be with their friends, then in five to seven years' time they go to another community."

To be considered a premium home, "8,000 to 10,000 square feet is the new threshold," Lemoine said. It was 5,000 to 7,000 square feet just five years ago, he added.

Buyers today want two sets of refrigerators and freezers, two game rooms (one for the kids, another for adults) and showers at least 7 feet by 7 feet, he said.

The high-end home market barely existed when Lemoine moved to Las Vegas from Southern California 21 years ago. Real estate agents say few if any houses sold for more than a million dollars before the mid-1990s.

That began to change as Las Vegas evolved into an upmarket destination, which Moehring traces to the opening of the Mirage resort in 1989.

That ushered in a new era in which gambling shared the stage with golf, spas and shopping. Soon, the Strip was filling up with world-class restaurants, boutiques and hotels.

This helped draw even wealthier visitors who bought second homes in the area, Moehring said, while also expanding the local population of wealthy professionals and casino executives.

By 2000, 176 Las Vegas homes sold for more than $1 million, according to real estate research company DataQuick Information Systems. By 2006, that number multiplied nearly eightfold — to 1,385 before ebbing to 1,219 last year.

Along with being out of date, developer Tom McCormick says a lot of the mansions built hastily during the city's real estate boom suffer from poor design.

Some used the wide-open lots in the desert to showcase fine architecture and good taste, McCormick said.

Many more did not.

"Just because you're a great entrepreneur doesn't mean you're a great home designer," said McCormick, president of midmarket home builder Astoria Homes.

The housing slump has left Las Vegas strewn with empty houses, and at all price points.

There are now more than 22,000 homes for sale here, 51 percent of them vacant, according to the Las Vegas real estate research company SalesTraq.

William Derentz, of Mission Viejo, Calif., bought a 5,400-square-foot home in Las Vegas for $2 million in 2004. He never moved in, since he planned to resell it in a year or two at a hoped-for profit of $1 million.

But after the home languished on the market, Derentz threw in the towel in February and relocated his family to the house.

He now hopes to sell it when the market recovers, even if that takes several years.

Meanwhile, he's spending $200,000 to fix up the backyard of the house, outfitting it with a pool and "his-and-her" cabanas.