Nothing quite like the simultaneous awe and dread of looking at a construction so gargantuan that you feel like an ant on the floor of a cathedral
Pic is by Étienne-Louis Boullée. Also if you're into this kind of stuff, check out the work of Giovanni Battista Piranesi. Also have a look at the short film The Centrifuge Brain Project.
I recommend the manga Blame! which takes place in a world entirely composed of one massive abandoned megastructure.
I remember learning about that one from a Jacob Geller video!