Few New Yorkers noticed earlier this summer when a dozen police horses boarded in a stable located in lower Manhattan for most of the 20th century were loaded into trailers and moved uptown.
The New York Police Department relocated the horses -- a quaint curiosity to neighbors living in high-end TriBeCa lofts and townhouses -- to build a temporary staging area for 220 officers newly assigned to protect ground zero.
The lower Manhattan force will eventually rise to 670 -- larger than any of the 76 precincts in the five boroughs and entire departments across the country. The multiple thousands of people who will visit the Sept. 11 memorial after it opens this fall will endure airport-style screening and be watched by hundreds of closed-circuit cameras when the attack site opens publicly for the first time since 2001.
While New York leaders say the resurrection of the 16-acre World Trade Center site may be viewed by most Americans as a triumph of the nation's resolve, law enforcement experts believe terrorists see it as another chance to prove their tenacity.
"Without question it is a target, because it has tremendous symbolism," said James Kallstrom, a former top FBI official who headed the New York City office in the 1990s. "Going back and attacking a landmark that was already attacked once is the ultimate challenge."
Developers and law enforcement have grappled with how to best police the anticipated steady flow of tourists, workers and commerce at the site without turning it into an inhospitable, armed camp.
Police plan to use a vehicle security center to screen tour buses, trucks and cars before they enter the site and park or makes deliveries using an underground roadway. Pedestrian traffic, including visitors to the museum, also will be screened before they enter the central plaza.
Ticketed visitors to the memorial will be funneled into a security screening room with airport-style metal detectors and X-ray machines. Employees and frequent visitors will be prescreened so they can bypass regular checkpoints.
The security plan also calls for 400 closed-circuit surveillance cameras in and around the trade center site.
Final touches are also being put on another ambitious piece of the plan: Screening every car, truck and other vehicle for radioactive materials -- evidence of a possible dirty bomb -- and other potential threats as they enter lower Manhattan.
The 220 police officers will start patrolling the site and immediate surroundings by the end of the month, in time for the memorial's opening on Sept. 11. Many of the officers have volunteered to undergo special counterterror training, including how to spot suspects doing reconnaissance at the site. They're also being drilled on use of heavy weapons and emergency medical response.
And eventually, the horse stable located 12 blocks north of ground zero will be restored when police officers get a permanent home, said Julie Menin, who heads the downtown community board of the neighborhood that includes the site.