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?