Hi everyone,
So I’m making myself a little game and I need to make a few large buildings. I wanted to know what your thoughts are on the best way to do it. I’m using Blender to handle all the modelling work at the moment
1: Create the whole building and import it like that.
2: Break it down into smaller pieces like walls and pillars and just put it all together in Unity.
I want to get some input on this before I start something so any help would be great.
The way you do it depends on your needs. Is the whole building ever going to change? Do you need modular pieces?
The whole building at once seems like the easiest way to do things. It lets you texture all of it at once, and assuming you create a single material/texture, it saves on draw calls, doing the whole thing at once. The disadvantage is that you can’t really change the model once it is Unity. Anything that moves(like doors) would need to be accounted for, either as animations, or as separate models.
Doing things as smaller pieces has advantages too. It is generally harder to do, because of modelling separate, and making things match, and the texturing pipeline is more difficult too. Also, it may not be as optimized as it could be due to having separate pieces. The advantage, if you make things modular, is that you can create new buildings out of the pieces, without having to make new models. Of course, this assumes you made the separate pieces in this modular fashion.
What your goals are ? Mobile or PC ?
One of the great example I can give you, (simple boxes texture greatly) is GodFather 2006 Published by Electronic Arts (EA) without knowing specifics of your goals and what are you targeting.
Well my target is PC. The reason I’m asking is because I’m making an asylum and the scene I need it for will only be played once. It will take place outside of the asylum and thus the reason for asking. The area will be a little large as you have to explore the grounds first. The building itself wont be changing and I’m planning on instancing the areas inside. So that’s about it. It’s a big building I have seen people build smaller building with pre-made walls etc and them some create the whole building as one asset. I just can’t make up my mind 
Go modular. with tools like Progrid (Unity Asset Store - The Best Assets for Game Making) which I think has a free version ( or basically the entire procore toolset) you will be really thankful you didn’t model the entire building in your DCC app ( plus, easier for texturing, lightmapping, making changes inside of Unity.) If you go the modular route, also look at batching tools ( Unity Asset Store - The Best Assets for Game Making, highly recommanded) to be able to combined everything when you’re happy into a few meshes to lower drawcalls and what not.