The assignment was to create a villain's headquarters, and map it into real footage that we camera-tracked. I leaned immediately towards a natural environment, and settled on the idea of an unseelie fae stronghold. Something that would both stand out starkly against the landscape, and blend in with it organically.
I chose to build a dark, arcane-looking castle on a mountainside, with fantasy-color trametes fungus, glowworms, and fireflies.