Another combination of existing pictures. Son Doong cave, one of the biggest cave in the world. I daydreamed of entering that cave, back in Vietnam, but the 10k USD fee convinced me to see its little sister, the Hang En cave, which is just as majestic, just not as gigantic (and wallet-eater). The cathedrals are sort of coming out of memory. I used Notre-Dame-de-Paris as a reference for the very very very small left corner, with the fire, see.
CS3; x hours; ref pic.