Area 52

A pyramid, which resembled the Great Pyramid of Giza from the Doctor's World, was used as the base for Area 52 in an River Song's World.

River Song secured the location through the use of her hallucinogenic lipstick on President Kennedy and by pointing a gun at Cleopatra.

The building was used to house over a hundred Silents, as well as their agent, Madame Kovarian. River built a timey-wimey distress beacon on top of the pyramid. She later married the Doctor on the top of the pyramid and kissed him — actually the Teselecta — reverting the timeline. (TV: The Wedding of River Song)