The Pentagon
The Pentagon was a building in Washington, D.C. (TV: The Claws of Axos) that served as the centre of the United States military. Its inner sanctum was the National Military Command Center on the third floor, and it was connected to the White House Situation Room by a permanently-open telephone line. (PROSE: Option Lock)
During the late 20th century, the Pentagon was one of the research centres and capitals to which Axonite was distributed. (TV: The Claws of Axos)
In the Monks' Shadow World, Bill Potts and Nardole stumbled across a holographic version of the Pentagon made by the Monks as a practice for their conquest of Earth. (TV: Extremis)