Great Pyramid of Giza

The  was where the timey-wimey distress beacon was built by River Song in an alternate timeline where all of history occurred at once. The timeline came into being because she refused to kill the Eleventh Doctor. The King's Chamber was where they had Madame Kovarian tied up. River was married to the Doctor on the top of the pyramid and she kissed him -- actually the Teselecta -- reverting the timeline. (DW: The Wedding of River Song)