This episode is everything everyone says DW is but often the show is not. For one thing science marvels are introduced in the TARDIS and without. The sets are atmospheric and somewhat clastrophobic, the petrified forest and the metallic petrified animal lizard thing are most unusual. Then there's the city...even more clastrophobic. The WHOLE thing is very alien and this takes it time and does not rampage us with humanoid aliens any time soon...just one hand that touches Susan's shoulder in one scene and the hammering sound outside, heard from within the TARDIS (unusual in itself maybe but it was on the scanner) makes this entire thing just eerie. It is truly a classic ep as the foursome venture outside and together and separately explore the forest and later, the city, thanks to some sabotage by the irksome Doctor, who also displays quite a bit of charm.
The characters start to cement themselves together, despite differences; Susan's flower is forgotten about by Ian who crushes it by accident without even realizing it...to rush to Barbara's aide... a matter of survival perhaps. And again later, Susan's flower is forgotten about by her when she senses something in the forest and Carole Ann Ford is so good here. Later in the ship in a Food Machine Room (an amazing machine indeed and an idea that food can be made smaller will be one that astronauts will use I think and in LOST IN SPACE they are pills!), Barbara relates to Susan as the Doctor had hoped. Ian also seems to be leading even though in AN UNEARTHLY CHILD by ep4 or so, Ian told Kal that the Doctor was their leader. Ian is certainly braver and more strong. The Doc here sometimes talks to himself, sometimes mutters, and sometimes flubs but not much.
Barbara's getting lost in the smaller and metallic almost antiseptic maze of the city below is something of a vast achievement for the show, creating rising terror and a feeling of being trapped in a giant maze. I'm not sure the elevator can be seen as an elevator but it is and that cliffhanger is a gem of a classic as the plunger moves in at Barbara when the lift opens! And she screams and the theme music starts! Just great. I felt bad for her but the travelers should not have separated and this entire ep is just a great one, giving us a sense of adventure, mystery, danger, alien-ness, and terror and a feeling of being out there somewhere out of your depth. Ian tells Barbara to just believe they will get home.
I like Ian saying he hopes his food doesn't have a tinge of ancient Greece and the Doc says of the bacon that it should not be salty because, "It is English"---a Hartnell ad lib.
The Doc just wants to go explore the city and the others talk him out of it but he has plans of his own and the ship is out of mercury in the fluid link. Ian says, "Fellow Travelers" and some of fandom's lingo starts in this very episode.