(CBS) The U.S. government already has a courthouse at Guantanamo Bay, but the Pentagon isn't satisfied, CBS News correspondent Sharyl Attkisson reports. It plans to spend $100 million of your tax dollars to build a huge new facility just down the hill.

"This is very expensive for the number of cases, 60, which they anticipate trying," says Sen. Dianne Feinstein, D-Calif.

That's right, a $100 million courthouse to try about 60 cases. That's $1.6 million per defendant ... just for the building. The trials will cost many millions more.

Of course, these aren't run-of-the-mill defendants. They're terror suspects including 9/11 mastermind Khalid Sheik Mohammad. Still, both Republicans and Democrats in Congress are balking at the idea — and the cost — in private meetings with Defense Department officials.

"I asked them if they had looked at alternatives in the United States, looked at them, and the answer was no," Feinstein says. "I was surprised that they hadn't looked at Fort Leavenworth, at other places to build a courthouse, to bring these people over, to keep them in secure custody, to try them."

But this building will house more than courtrooms. The courthouse would sleep up to 1,200 people, there would be a dining facility for 800, and a garage big enough for 100 vehicles.

Tax watchdog Tom Finnigan of Citizens Against Government Waste says his radar antennae went up when the Pentagon recently tried to push the plans through Congress on an emergency basis without any votes.

"They tried to rush the funding through the process. That alone raises a red flag this could be a boondoggle in the works," Finnigan says.

No one from the Defense Department would agree to an interview, but a spokesman told CBS News the new facility is needed so more than one defendant at a time can be tried under heavy security. The trials could take years, and the space allows for lots of observers and reporters for maximum transparency, the Pentagon says.

It looks as though there's enough skepticism on Capitol Hill that the Pentagon will have to put the project through the formal processes in January, so Congress can actually vote on whether to spend $100 million of your money on a very special courthouse.

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