No time to design the ballroom or choose the fountains? $17.5 million gets you a ready-made mansion today . . .

Have you noticed the empty mansions for sale? Sure, some extravagant new houses are on the market because times turned harder for the original buyers. But the Washington area also has a supply of off-the-rack mansions, built for wealthy folks who don't have time to wait for a custom house but would rather not live where strangers used to reside.

They may be on McLots -- parcels as small as two acres -- but these houses are hardly tract-built McMansions. They're the real thing, with ballrooms and dining rooms that can accommodate a banquet meeting any baron's standards.

Last week, I toured one of the most expensive houses for sale in the Washington area, a six-bedroom, French-style brick chateau in McLean. Under construction for four years, it went on the market in April. Asking price: $17.5 million.

Workers were still building the gated front entry when I arrived. Most of the basement remains unfinished, ready for the eventual owners to decide whether it should have a bowling alley, home theater or whatever. Those upgrades aren't included in the $17.5 million price, but that could be a negotiating point.

I was led on the tour by owner/developer Michael Darvishi, president of Noble Construction. He said he and his wife, Goldie, originally planned to live in the home but gave up on the idea about six months into construction. "I decided whatever I'm living in now, I'm happy in," said Darvishi, who lives in Great Falls. The new house is dotted with fountains, marble mantels, stained glass and other pieces he and Goldie picked up at auctions.

Nothing about the house is understated -- or particularly home-like, really. The main entrance is set for Cinderella's arrival, with a sweeping stairway, filigreed wrought-iron banisters and a dome that hints of the main reading room at the Library of Congress. There's marble everywhere, crystal chandeliers, gilded trim, even a secret staircase worthy of Batman.

For $17.5 million, you also get such practical touches as alarm systems, an elevator, a massive safe (brought in with a crane) and an equally massive backup electricity generator. For all that cash, though, you don't get sewer service. The house is on a septic system.

The 27,000-square-foot house sits on only about two acres of land. Many of the deciduous trees that provide privacy actually belong to the neighbors, and come winter, that privacy will be gone. The mansion is jarringly out of scale with its suburban neighbors.

Darvishi's broker, Jonathan Taylor of Tutt, Taylor & Rankin, the local Sotheby's affiliate, said the house has drawn nibbles of interest from people in the entertainment business, "upper-echelon" athletes and foreign buyers. "There's foreign money that sees things as affordable here," he said.

That's largely thanks to the weak dollar, which has turned the United States into a Filene's Basement for visitors. A new study from Mercer, an international human resources consultant, ranked the Washington area only 107th on its worldwide list of most-expensive cities, thanks in part to the weak dollar. Our cost of living for expatriates is cheaper than in New York, Los Angeles, Miami and other U.S. cities, not to mention Moscow, Tokyo or London.

But marketing one of the most expensive homes in the area still can take a while. "You might expect a year on something like this," Taylor said. The pool of buyers able to afford such homes is relatively small -- and they tend to be a mite picky.

With six listings, McLean has the greatest number of homes on the market for $10 million or more. The District has four, according to a search of the multiple-listing service. Bethesda has one. For all its acreage and horse pastures, Great Falls doesn't have any listings in that range. I was surprised to see that Potomac had no listings over $10 million, although it has nine priced from $5.125 million to $8.5 million.