I also looove the architecture of the vex. First time landing on venus you see the strange towering monument that is the Citadel, looming over you. It's at the same time both ancient and archaic, and technological and futuristic, like a giant computer network. And then you get to climb it!!!! So fun to ascend over the clouds and jump across that insane computer in the sky. Then you descend into the vault, and see how the vex have integrated their tech into the planet itself, with glasslike structures and square computer relays in tandem with towering rock spires and boulders. BUT THEN THERE'S THE HIVE. The twisted catacombs and temples under the moon. The disgusting breeding grounds on earth. And the Dreadnaught. Oooooh, the Dreadnaught. This is the hive's Notre Dame, their coup de grace. Just walking in it inspires awe, how huge it is, all the space and the eerie light casting shadows from those giant pillars. All in all, bungie's world design is on point. The huge seige machines of the cabal towering over mars, and the ketches of the fallen on venus and earth, the siva invested splicer dens of the plaguelands. Even the space goo of the taken adds a new dimension to the world.