The Ark in Space.
A good story, well ahead of the effects ability's of its day.
The Pyramids of Mars
. Neat. Enjoyed this immensely! [potential spoiler ahead]
Is the Doctor trapping Sutekh
within the Time Corridor
the reason why lightning strikes the TARDIS in the opening credits, Sutekh is attempting to attack him? I like to think so... unless there's another reason I am not aware of?