New York has survived a mighty terrorist attack, colossal blizzards and other major disasters in the city's long and storied history, but nature threatens to throw one of the biggest blows yet this weekend as Hurricane Irene takes dead aim on the Big Apple.

Before the powerful Category 2 storms reaches New York at projected hurricane strength the storm will have cut a path up dozens of other cities along the east coast, but no city is arguably more important to the U.S. and the world as New York. With almost nine million residents, and global transportation and financial hubs, New York's vulnerability to a major hurricane suddenly looms large.

Mayor Michael Bloomberg and other key officials have made no doubt about the potential severity of Irene. They have ramped up preparations, including evacuations and a planned shutdown of the city's mass transportation system in the effort to minimize risks to individuals.

But even still, the threat of a rare major hurricane making landfill with a direct hit on New York poses many risks.

Even the New York Stock Exchange says Irene could cause a shutdown on Monday.

If we can open here but none of our customers can get to their desks, it really doesn't make a lot of sense to open the exchange, Louis Pastina, senior vice president for NYSE Euronext, said in a Bloomberg Television interview. We'll have to gauge that in coordination with the Securities and Exchange Commission, the other stock exchanges and our member firms.

By late Friday, the concerns were much bigger, however, than whether the financial markets would be able to open Monday. The city, in Manhattan at least, may be made mostly of steel and concrete, but though hurricane force winds may not be able to topple tall buildings the damage potential and risk to life in the high-population concentrated city were looming large.

Among the greatest risks to New York from Hurricane Irene:

--Damage to vital infrastructure. Among the first evacuation orders issued Friday by Mayor Bloomberg was a mandatory order for the city's financial district. Low-lying and surrounded by water, a significant storm surge could cause major damage to key properties in the area that fuel commerce, including the financial markets.

Any interruption in the city's financial district from a big hurricane force storm surge would be costly. Also, the city's infrastructure is vulnerable at key access points and roadways that shuttled tens of thousands to and from Manhattan each and every day.

--Catastrophic flooding. New York's subway system built for the most part just one floor down, particularly in the downtown area. Heavy rains have been known to flood subway stations, but New York has never experienced a direct hit from a hurricane force storm since the subway system was built. If subway lines and stations were doused with salt water pushed in from Irene, the corrosive effect could be long lasting and quite impacting.

In August, 2007, for instance, a surprising storm of torrential rains paralyzed New York City's transit system. Every one of the city's subway lines was disabled or delayed.

The cause of the cascading outages across the mass transportation system this morning was the inability of our drainage system to handle what was, we believe, three inches of rain within a one-hour period, said former New York Gov. Eliot Spitzer, who at the time ordered the Metropolitan Transportation Authority to conduct a review of how the subway shutdown happened.

But one can easily surmise that if a surprise storm dumped several inches of water in New York and it shut down the subway system what a hurricane like Irene might inflict.

--Airline transportation interruption. Some surverys suggest as much as 25 percent of all U.S. airline travel is reliant upon the New York area's three major airports in one way or another. JFK in Queens County, for instance, is quite exposed right on the water. The airport, the city's major international terminal, could easily be damaged from a major hurricane, thrusting transportation to and from the city into disarray.

Such damage, likely at some level in a direct hit, would have a cascading impact across air travel throughout the U.S. and world.

--Economic impact. No city is as important to America's financial health than New York. Long term the recovery effort by New York would spawn new dollars in the economy, but in the immediate term a city slowdown due to office closings and tourism that could be lessened by air travel interruptions could cause a big dip that would likely show up at key economic numbers.