Today, we have a *very* informative guest post by Mike Freiberg.  Mike is a staff writer for HomeDaddys, a resource for stay-at-home dads, work-at-home dads, and everything in between. He’s a handyman, an amateur astronomer, and a tech junkie, who loves being home with his two kids. He lives in Austin.

It isn’t the biggest, or the flashiest—but it’s definitely the priciest

The new One World Trade Center (or Freedom Tower)  has been a difficult project to get moving since it was announced nearly twelve years ago. Numerous architects and dozens of possible designs were considered, and ultimately scrapped, as the project underwent one reinvention after another. The project was finally completed May 10^th of this year, rising to a symbolic 1,776 feet, and running up a bill of just under $4 billion—making it (by far) the most expensive skyscraper ever built.

For comparison, the Burj Khalifa, currently the tallest building in the world, dwarfs One WTC by over 1,000 feet, and is much more lavishly appointed—but was built for less than half the price ($1.5 billion). So where did One World Trade Center’s nearly $4 billion price tag come from?

The world’s first fortress skyscraper

The Freedom Tower designers had to juggle several competing priorities. The tower shouldered a heavy rhetorical burden, as a symbol of fortitude and resilience—but it also had to meet the pragmatic needs of a global financial hub on an extremely valuable piece of real estate. It was a tall order; but by far the most expensive and challenging aspect of Freedom Tower’s design was security—demonstrating that the lessons of the 9/11 attacks would be taken seriously.

From the exterior, One World Trade Center looks like any other skyscraper. Inside, though, it’s built like a tank—and incorporating (and concealing) these features was the greatest source of cost overruns during the tower’s seven-year build. Here are a few of the most impressive innovations.

A towering concrete base

Unlike most skyscrapers, One World Trade Center is set on a 20-story, windowless podium of highly reinforced concrete, built to withstand a 1,500 lb. truck bomb of the type used in the 1993 World Trade Center bombing. When completed, the podium will be sheathed in prismatic glass to conceal the blast walls. The podium uses 720,000 cubic feet of “iCrete”, an expensive designer concrete mixture capable of withstanding 14,000 pounds per square inch of pressure—nearly three times the compressive strength of normal high-rise concrete.

A colossal air-quality apparatus

While the exterior is fortified against explosions and impact, designers also considered the threat of biological and chemical attacks, as well as fire, sparing no expense for One World Trade Center’s internal air system. Each stairwell is composed of reinforced concrete, with a separate, pressurized air supply to keep them operational in the event of an emergency.

The building is also dotted with biological and chemical filters and detectors, as well as ventilation shafts that can quickly expel contaminants as soon as they are detected.

Fortified, secure elevator shafts

One World Trade Center’s elevators are encased in three feet of concrete, and serve as an internal “spine” for the building, to prevent collapse in the event that the steel exoskeleton gives way (as it did in the September 11^th attacks). The tower contains 71 elevators, none of which have buttons—instead, the car identifies each passenger, and will only bring them to the floor for which they are authorized, at an impressive 23 miles per hour. It remains to be seen how smoothly this system will operate—the building will open late this year.

An integrated security and safety network

Perhaps unsurprisingly, Freedom Tower will feature over 400 closed-circuit surveillance cameras, networked security doors, temperature and air quality monitors, and automated elevators connected via a huge web of shielded communications cables. Security teams will have a constant stream of richly-detailed status reports from across the building, so that even minor problems like electrical failures or a buzzing smoke detector reach security instantaneously. Early on, this security grid will also incorporate airport-style checkpoints and electrified fencing on the tower grounds, but those measures will be phased out after several months of normal operation.

Of course, these mammoth security expenses have been highly controversial—what seems like an appropriate symbol of vigilance to some, manifests paranoia to others—but however you interpret them, it’s not all that surprising that One World Trade Center is now the world’s most expensive skyscraper.

Thanks, Mike, for the detailed information on the newest symbol in the NYC skyline. 

What do you think about the Freedom Tower?  Is it money well spent?  Over-engineered to death?  Share in the comments section, below.