12 December

On 12 December 2360, the Eleventh Doctor and River Song visited Calderon Beta, where they encountered two future versions of River and one of the Doctor. (HOMEVID: First Night, Last Night)

On the same day in 1901, while on an expedition to the ruins of Babylon, time sensitive linguist John Lafayette stumbled across the Path to Babylon, circa 570 B.C.. (PROSE: Walking to Babylon)

In 2003, the Sixth Doctor and Melanie Bush met up with Mel's uncle, Dr. John Hallam, at the centenary celebration for the National Foundation for Scientific Research (UK) in Berkshire. Hallam became a temporary companion of the Doctor when the duo had to use the TARDIS to go back in time to 1782 to save Mel from a temporal paradox involving a Hallam family ancestor. (AUDIO: Catch-1782)