:D I love cathedrals. How big we talking?
I want to build a 2 stack wide, 4 stack long masterpiece of a cathedral. Sadly I doubt I could get the resources and handle the lighting for such a thing.
Hmm, well it won't be as big as that

It's 53 blocks long, and at it's widest is 31 blocks. Not entirely sure how high I should make it yet. I am also going to need to mine extensively in the nether as I need the light stone for my stained glass windows (the texture pack I am using looks a lot like stained glass)
And yes, the lighting will be a task on itself after-wards. I am hoping the lightstone provides enough light to not make it quite so daunting a task.