The Doctor - the last of the Timelords - has visited all
dimensions of time and space, but the following two times (both in
UTC) will lead you to the hidden secret that you seek.
21:29:40, 27th Feb 1971
19:19:10, 12th Jul 1975
If you are
successful in your quest, leave your mark,
but please make sure you hide it well when you depart - you
never know when the Daleks or the Cybermen are going to show
up!
Greenblat