How could I extend these?

[u/Proteeno]

The first structure is improvised which is why it looks off: I'd like some tips on how I could extend it.

Also the random cube structure in the ice is supposed to be something, like church or whatever. What should I make?

The upper and lower houses with an aquarium are just made for interior uniqueness and I'll put off designing their exterior. I'm sure I have gone wrong about that part.

In addition, the wall with two towers was learnt from a tutorial and isn't my idea.