London – The new American Embassy in London is the most expensive in the world and includes safety features like a small moat.

The new structure, reported by the Times of London to cost $1 billion, would set a glittering jewel in the crown of American presence abroad, even as soaring deficits and unemployment continue to threaten the economy at home.American diplomats will be trading their prime real estate near London’s luxurious Mayfair for a spot along the Thames in the industrial neighborhood Battersea. The move has been motivated by security concerns and overall decay at the current site, said U.S. Ambassador Louis Susman.

“We will replace our current embassy, which has become over-crowded, does not meet modern office needs and required security standards, and after 50 years is showing signs of wear and tear,” he said in prepared statements.

The current U.S. Embassy was designed in the 1950s by the American architect Eero Saarinen, who eschewed his usual soaring modernism to create the blocky and much-derided structure that opened in 1960.

The new embassy, designed by the Philadelphia-based firm KieranTimberlake, features far more amenities in its 500,000 square feet, including lofted halls and beaming “light art,” a bit of aesthetic diplomacy the State Department hopes will be more popular than the old embassy’s ominous bald eagle sculpture that has glared down at passing Londoners for 50 years.

And it is Britons who may be benefiting most from the new construction, said Williams, who did not expect to see many jobs created for struggling American workers in the massive project.

The State Department’s Bureau of Overseas Building did not respond to e-mail and phone requests for comment.

The new crystal fortress would be the most expensive embassy ever built, easily topping America’s sprawling compound in Iraq, which cost taxpayers some $700 million and was completed over-budget and years behind schedule. A new embassy in Pakistan is projected to cost $850 million.

This compound, in much less danger than its counterparts in Baghdad and Islamabad, was proposed by James Timberlake, an architect as a metaphorical outreach to Britain, a “beacon that is a respectful icon representing the strength of the U.S.-U.K. relationship.”

The building’s designers imagine it as a timeless but ultra-modern update, an energy-efficient, carbon-neutral, self-sufficient work of art that will contain an urban park replete with ponds and pleasant sculptures.

Groundbreaking for the new embassy is planned for 2013 with an expected completion date in 2017. But Williams, who has followed similar government construction projects, considers that a rose-tinted estimate at best.