In New York City, both saunas and health spas are a thing of the past. What is becoming a trend in the city's real estate is the installation of the in-house "safe rooms" which are made of Kevlar and steel. By having a safe room, homeowners believe that they will be protected from any imminent threats such as bombs, terrorist attacks and the like, a report from Amny said.

According to the report, local security experts believe that safe rooms could be very beneficial to homeowners as these could be utilized when there's an economic collapse, a revolution and civil unrest. They claim that safe rooms have become a necessity for households.

In fact, at least 1 percent of the residences in Manhattan have a safe room, according to Jonathan Miller, president and CEO of Miller Samuel, a real estate appraisal firm. Miller said that the popularity of safe rooms, however, has accelerated with the rising value of the real estate property.

"A safe room - a bullet-proof, ultra secure confine which can cost more than $500,000 to build - is starting to become a part of the suite of amenities that makes a property part of the upper end of the market," Miller  said,  as quoted in the report.

He pointed out that townhouses which have safe rooms can be found in areas with low incidence rate of petty crimes such as robbery, burglary and murder. He stressed that that these townhouses are usually located in some of the safest community in the metropolis.

Tom Gaffney, CEO of Gaffco Ballistics, said that the demand of safe rooms began after the 9/11 attacks. Gaffney said rich people are always afraid that something might happen to them. "The more you have, the more you have to keep safe," he further said, as quoted in the report.

"Safe rooms were popularized as 'panic rooms' by the director David Fincher's 2002 thriller of that name - one that the screenwriter David Koepp has admitted he made up because safe room did not carry quite the same drama at the box office," The New York Times said.