As the housing boom rolled richly over Placer County, Westfield Corp. decided to expand its fabulously successful Roseville shopping mall.

Today, the first phase of a stunning, $240 million addition to Westfield Galleria at Roseville debuts in a different world, amid the worst economic turmoil in decades.

As doors open at 10 a.m. to a fresh lineup of retailers, so too begins the speculation.

Will Galleria shoppers dig into their wallets even as consumers nationwide are holding back after a battering to their portfolios and home values, and rising uncertainty over jobs? Will they dig deep enough to support 100 new stores, including the eventual arrival of luxury retailers like Tiffany and Co.?

If there is a retail market that can answer yes to these questions, it may be the one surrounding the Galleria.

Within 15 miles of the 8-year-old shopping mall, more than a million consumers live in households earning well above the region's average. Two-thirds own their homes and seven in 10 workers drive to white-collar jobs, according to researcher Claritas. There is very little poverty.

Analysts point to other positives. In a slumping real estate market, new homes still sell faster in Roseville than any city in the Sacramento area. Placer County is poised for continued strong growth, a key factor for Australia-based Westfield, which owns 58 U.S. malls and says it thinks 10 years ahead.

"I just got back from opening our new mall in London. The question that kept recurring there is the same here: Why now?" said Westfield spokeswoman Katy Dickey.

Said Dickey, "We're a long-term owner that invests through all economic cycles. We'd love to open during an economic boom. But consumers won't stop spending or shopping."

If the mall expansion proves a winner it will stand in sharp contrast to much of the area retail scene.

In Elk Grove, the 1.1 million-square-foot Promenade shopping mall is stuck in a holding pattern. Its developer, General Growth Properties Inc., a Westfield competitor, said this week that debt problems are threatening the company's future.

The Galleria has competitive implications for other shopping areas, as well. As the economy tightens, Arden Fair mall, Sunrise Mall and other areas will have to ensure that any success enjoyed by the Galleria expansion doesn't come at their expense.

Shoppers will find plenty of new opportunity at the Galleria. The mall's 400,000- square-foot addition initially features 48 stores, including:

• H&M, a trendy men's and women's clothing chain based in Sweden.

• Louis Vuitton, a France-based luxury fashion and leather goods store.

• Lush, a hand-made cosmetics chain based in the United Kingdom.

Westfield declined to give more details, saying many stores wouldn't be known publicly until today's openings.

Another 52 stores will open in coming months, says Westfield. They include popular retail brands such as Oakley, Sephora, Lululemon, Burberry, Juicy Couture, LaCoste and Tommy Bahama.

The big shopping buzz, however, is for jeweler Tiffany and Co., which calls itself the "world's premier jeweler." The Galleria will house the chain's sixth store in Northern California when it opens later. Currently, the closest Tiffany's to the capital region is in Walnut Creek.

Some experts believe the jeweler's cachet in itself will spark new trips to the Galleria.

"Any time you have a retailer like Tiffany's it's a draw," said Bob Gordman, a Colorado retail consultant. "Unique stores like that make a center a destination that people will drive a long way to visit."

Kathryn Boyce, a Placer County resident, tracks the region's builder- and retail-friendly demographics for home-builder consultant Hanley Wood Market Intelligence.

She says, "They're taking shops considered to be Bay Area shops and putting them in Roseville. They know what people want out here and what people can afford out here."

Rocklin retiree Ross Harris, 86, is among those excited to see the expansion. A regular mall visitor with his wife, he says the gossip is "it's going to be really, really nice."

Call The Bee's Jim Wasserman, (916) 321-1102. Read his blog on real estate, Home Front, at www.sacbee.com/blogs.