As other real estate empires collapse, Boston Properties is getting ready to go on a shopping spree. The hometown real estate giant is primed to scoop up billions in top-notch office towers from owners that may have overpaid during the bubble years and are now looking to bail out – just one of many ways in which the publicly-traded real estate giant is thriving during one of the bleakest stretches for commercial real estate since the 1930s.

While vacancies in downtown towers are at highs not seen in decades, Boston Properties’ portfolio is mostly full. And even as other developers sit staring at empty holes where skyscrapers were supposed to have gone up, the real estate giant has managed to hit home run after home run when it comes to building new towers.

“To be honest, I guess you can say they are lucky, but by doing their homework, they seem to be luckier than others,” notes David Begelfer, chief executive of NAIOP Massachusetts, which represents developers across the state.

If there are any Boston Properties doubters out there, just look at the $700 million the company just raised as it eyes a commercial real estate sector filled with juicy acquisition possibilities.

Lots of firms would like to be buying now, but more than a few major players are instead desperately ditching assets to raise funds amid growing pressure to pay back their lenders.

But not Boston Properties. The firm estimates it can leverage the $700 million it recently raised and other cash on hand into more than $3 billion in buying power as it scouts for bargain properties in a down market.

“We are also trying to position ourselves to take advantage of what opportunities we think will be coming down the pike over the next year or 18 months,” Mortimer Zuckerman, the firm’s chairman, recently told Wall Street analysts.

Talent Show

Our hometown real estate giant is now in a position of strength thanks to top talent at its Prudential Tower headquarters and shrewd management of its office tower portfolio.

Overall, it’s a richly talented team. There’s Zuckerman in the chairman’s office, who has carved out a media empire to go along with his towers (he owns The New York Daily News and U.S. News & World Report, and is a regular on the political talk shows).

There’s also the steadying presence of President Doug Linde, who is taking on a larger role after the recent death of his father, Ed Linde, co-founder of Boston Properties and its long-time chief executive.

And below the big guys is a roster filled with top real estate talent. Boston Properties has earned a reputation for hanging on to its brightest stars in a business where jumping from one shop to another is typical.

That investment in talent appears to be reaping dividends for the company.

Downtown Boston is bleeding empty office space, with the vacancy rate having hit 20 percent, a low not reached since the brutal 1990s downturn. But while there are huge blocks of space in towers across the city, you will be hard-pressed to find gaping holes in the sky-rises Boston Properties controls.

The company touts a less than 8 percent vacancy rate in its overall portfolio. In New York and Washington, D.C., that rate falls to 2 percent.

And when a tough hit comes along – like the loss of a major tenant – Boston Properties has a playbook for that as well.

BXP, as it is known by its stock ticker, just saw financier Bain Capital fly the coop at its tower at 111 Huntington Ave. in Boston, and go to the Hancock tower.

But if Boston Properties’ past record is any indication, that gap will be short lived. Faced with the decision by Gillette Co. to shift its headquarters from the Prudential tower to its own South Boston research and manufacturing complex, BXP reached out and struck a blockbuster deal of its own.

Boston Properties lured white shoe law firm Ropes & Gray over from International Place, filling nearly 500,000 square feet in the Pru and leaving a gaping hole in the financial district.

“They know what they are doing,” said Larry DiCara, a local real estate lawyer at Nixon Peabody. “They positioned the Prudential Center very nicely.”

Making Tough Look Easy

Meanwhile, Boston Properties used another neat trick as it built up one of the nation’s strongest real estate concerns – mastering tough, hard-to-build-in markets that often frustrate other developers.

BXP makes no bones about the fact that it has chosen to spend billions upon billions buying and developing in only four key markets – Boston, San Francisco, New York and Washington, D.C. All are high-barrier-to-entry markets, meaning once you are in, competitors looking to get in on the action can go pound sand.

Just take Boston, where the combination of a tough review process by City Hall, a mayor who knows a lot about development and expects a lot and very aggressive neighborhood groups have chased more than one would-be master builder out of town.

You won’t find the executives over at Boston Properties Pru tower headquarters shedding any tears about the Hub’s torturous permitting process, though.

“We are in the same markets that we have underscored before, namely supply constraint markets,” Zuckerman recently told analysts. “In Washington it’s because of a height limit; in New York because of the lack of available sites; in Boston because of an unbelievably complicated approval process.”

Finally, BXP has exhibited exquisite timing when it comes to building new towers.

There’s a graveyard of ill-fated tower plans that never went anywhere in Boston, still-births by developers who missed the market by a mile.

It’s quite a lineup, one that includes John Hynes and his hole-in-the-ground Filene’s tower; and Nicholas Pritzker, the Chicago billionaire who spent decades trying to build a mini-city on Fan Pier before he finally threw in the towel and sold.

Boston Properties, by contrast, hit a home run in the late 1990s when it built its 111 Huntington tower in the Back Bay, and is well on its way to hitting another one over the fence with Russia Wharf.

While other tower projects have stalled, BXP inked a deal with Wellington, a top financial firm, to occupy most of its Russia Wharf tower.

Mission accomplished, once again.