Luis Martinez / ABC News

Turning a lot of heads today  in a Pentagon hallway is the once-classified scale model of Osama bin Laden's compound used to plan last year's Special Operations raid.   It marks the first public display of what was once America's most secret scale model.

Hundreds of civilian and military employees at the Pentagon have spent time today gawking at a  temporary display that includes the tabletop model of the compound in Abbottabad, Pakistan that bin Laden used as his hideout for five years.  The compound itself no longer exists as the Pakistani government ordered that it be razed to the ground shortly after the raid last May.

Under a glass canopy is a model built by  National Geospatial- Intelligence Agency (NGA) model makers who used overhead satellite imagery to create a 3-D view of  the compound in painstaking detail.   The agency manages the network of intelligence gathering satellites and distributes that information throughout the national security apparatus.

A NGA fact sheet vaguely refers to the model as having "traveled extensively, including to the White House for use at senior-level briefings."

As the intelligence community began to suspect that bin Laden might be hiding out in the compound the model was built to help President Obama and the limited number of top officials briefed on his potential whereabouts so they could visualize what they were seeing on satellite photos.

Image Credit: Luis Martinez / ABC News

Built over the span of six weeks the styrofoam model was made to scale and shows the walls and infrastructure inside the compound's walls.  Every shrub and piece of ivy lining the walls seen in the satellite pictures is accurately represented in the model.  The model's scaling is one inch represents 7 feet.

"Model making is one example to replicate what people are seeing from imagery," said Karen Finn, a spokesperson for NGA.

She said the model is one of several built by the agency to help senior administration officials, as well  as military personnel involved in the planning and carrying out of last year's raid on the compound.

"That's what we do at NGA," said  Finn. "We provide geospatial intelligence information on all sorts of national security issues."

Because operational and planning details for last year's raid were some of the most tightly held secrets in the U.S. government, the model was a closely held secret.    Information about the bin Laden compound was so tightly held that analysts at various intelligence agencies knew only the compartmentalized information they were supposed to know.  It's likely that the NGA model makers had no idea that the model they built was housing the most wanted man on the planet.

The model has now been declassified and since last October has been on display in the lobby of  the NGA's headquarters in Virgina.  But you can only visit that facility if you're conducting business so today's display marks   the first time it's been publidly displayed, even if it's for only one day at the Pentagon.  .