I'm in love with your byzantine buildings, big fan of that kind of stuff!!
I'd like to share a little trick concerning the use of textures in painting, if I may! In rendering, textures have a maximum amount of textural detail when the light hits them sideways or at a tangent. This side-lighting highlights the bumps and cracks. Textures have the least amount of contrast & textural detail when in the shadows, and a happy in-between when directly lit. Direct lighting does not give a lot of textural contrast, but very high local color contrast.
This means a wood texture is going to be most contrasted at the interface between light and shadow because it's a physical texture with bumps and cracks. A wall paper or carpet texture is going to be more contrasted in direct light, because it's a flat texture of local color & value. Both of these have greatly lessened contrast in the shadow.
By controlling the opacity of the texture depending on whether it's in shadow, light, or at a transition plane, you'll be able to get a more photo-real result. This is a bit tedious because it means you have to map shadow and light accurately, but based on your previous rendering exercises, I'm not too worried about this being outside the scope of your learning.
Keep it up, love the dedication and hard work!!