The U.S. Department of Defense owns more than half a million properties worth in excess of $800 billion dollars. The military’s real estate holdings span the globe and, all together, sprawl across 30 million acres.

Pentagon auditors can’t explain what half the properties are for—and doesn’t have a plan for finding out. All this according to a Sept. 8 report from the Government Accountability Office.

The nearly trillion-dollar real estate glut is merely another example of egregious military waste.

Way back in 1997, the GAO identified the Pentagon’s real estate record-keeping as a “high risk” problem. The Defense Department could sell unused facilities and save billions.

It just needed to figure out exactly what buildings it owned and how it used them all. But military bureaucrats made only passing attempts to find out. The Defense Department is probably still sitting on billions of dollars worth of properties it has no use for, despite 17 years of GAO goading.

“We found in September 2011 that DoD was limited in its ability to reduce excess inventory because DoD did not maintain accurate and complete data regarding the utilization of its facilities,” the GAO states in its new report.

The Pentagon won’t sell off facilities because it has no idea what’s going on in many of them. Nobody’s keeping good, centralized records. Individual property managers aren’t performing mandatory audits—and the Pentagon isn’t holding them accountable.

The Office of the Secretary of Defense is in charge of the Pentagon’s real estate. It uses software called the Real Property Assets Database to keep track of land and buildings.

In theory. In practice, the GAO found that the software “showed facility utilization data for less than half of DoD’s total inventory, and these data often were incomplete or did not reflect the true usage rate of the facilities.”