The Doctor Who episode "The Deadly Assassin" was famous for two things.
It was the only Classic Doctor Who episode where the Doctor wasn't traveling with a companion.
And it was the episode that revealed how many regenerations The Doctor and other Time Lords have. Twelve.
I personally believe that they came up with Time Lords having 12 regenerations because of a clock.
The Doctor is a Time Lord who travels through time. And what measures time? A clock. And clocks have 12 numbers on them.
But I'm not certain about this. I could be wrong.
Attack of The Cybermen was also famous for two things.
It was the first Doctor Who episode that was twice as long per part. About 50 minutes per part instead of the usual 25 minutes.
It was also famous because it was the only episode where the TARDIS was something other than a Police Box.
The TARDIS temporarily became both an ornamental dresser and an organ.
But by the end of the episode, the TARDIS became a Police Box again.
I want to be honest with you about something.
I hate the new "Doctor Who" show so much that it has ruined Doctor Who for me.
Doctor Who is no longer the same and it makes me sad.