I'm going to build a stone cathedral. It will have high arched ceilings, a large central dome, an adjacent cloister, stained glass windows, a graveyard, landscaped exterior, a crypt, and a couple large towers. It will eventually have multiple levels.

It may take a few attempts, but you can see the beginning of my first attempt below. This first attempt will be somewhat smaller - more akin to a community church. I have constructed the skeleton arches first. You'll notice it's in the shape of a cross, like many cathedrals.