The Empire State Building in New York has increased security personnel by 25% and added baggage-scanning machines at its five entrances to the tune of several million dollars.

FORBES: The Detour Economy

As Adam Levitin of Georgetown University Law Centre and Susan Wachter of the University of Pennsylvania pointed out in a recent paper on the causes of the housing bubble in America, it is impossible to borrow the Empire State Building in order to sell New York real estate short.

ECONOMIST: Bricks and slaughter

Skanska provides a detailed case study of how they were able to retrofit their New York City headquarters in the Empire State Building and first commercial building in Scandinavia to achieve LEED Platinum precertification.

FORBES: How Skanska Incorporates Sustainability in Their Business Model

Global landmarks that are going green on 17 March include Niagara Falls, the Leaning Tower of Pisa, Burj al Arab in Dubai, Table Mountain in South Africa, New York's Empire State Building and Berlin's TV Tower.

BBC: Queen answers Irish bid to turn Buckingham Palace green

The Helmsleys' real estate empire in New York at one time included the Empire State Building, the Helmsley Palace hotel, the Helmsley Building at the foot of Park Avenue and the Tudor City apartment complex in addition to several other hotel properties.

FORBES: The Queen Of Mean Is Dead

New York's Empire State Building, which has been derided by some in the real estate world as the "Empty State Building", has also had trouble filling out its offices.

FORBES: $1.2B For A Pretty Pickle

The mill was built around an iron frame in a technique adapted in the rebuilding of Chicago in the late 19th Century and for skyscrapers such as New York's Empire State Building.

BBC: Ditherington Flax Mill site designs viewed