i) births and deaths
11 March 1945: birth of Graeme Harper, director of three Old Who stories (including a large part of Warriors' Gate, for which he was not credited), ten New Who stories (counting Time Crash) and three Sarah Jane Adventures stories
11 March 1952: birth of Douglas Adams, writer of The Pirate Planet (Fourth Doctor, 1978) and Shada (unbroadcast but would have been Fourth Doctor, 1980), co-author of City of Death (Fourth Doctor, 1979) and script editor for Season 17 (1979-80); best known, of course, for other things.
11 March 1960: birth of Robert Glenister, who played Salateen in The Caves of Androzani (Fifth Doctor, 1983) and Thomas Edison in Nikola Tesla's Night of Terror (Thirteenth Doctor, 2020).
11 March 1963: birth of Alex Kingston, who plays Professor River Song in New Who.
11 March 1967: birth of John Barrowman, who plays Captain Jack Harkness in New Who and Torchwood.
11 March 2000: death of Charlie Morgan, who played Songsten in The Abominable Snowmen (Second Doctor, 1967) and the Gold Usher in The Invasion of Time (Fourth Doctor, 1978).
ii) broadcast anniversaries
11 March 1967: broadcast of first episode of The Macra Terror, which is the first to use the new opening sequence and therefore the first time that the current Doctor's face appears on screen before the story starts. The Tardis lands in a colony where people are behaving very strangely and are not on any account allowed to talk about the giant crabs.
11 March 1972: broadcast of third episode of The Sea Devils. The Master summons the Sea Devils from the sea; the Doctor repels them from the beach but they attack the prison.
11 March 1978: broadcast of sixth episode of The Invasion of Time, ending Season 15. The Doctor destroys the Sontarans with a D-Mat gun - hooray! Leela stays on Gallifrey with Andred - Boo!
iii) date specified in-universe
There is a poster for British Science Week 2016, starting on 11 March, at the back of Miss Quill's classroom in The Coach with the Dragon Tattoo (Class, 2016).
It took me a while but I eventually spotted it. (British Science Week apparently had ten days that year.)
This is also the episode in which we see a lovely shout-out to the very first of the regular characters to speak in Old Who: