Research & Development
There are lots of images to showcase for the visual research. I'm missing a bit of the structure research.
Creative Art
I like the use of colors a lot, they bring very magical and fantastic feeling. The lighting only adds to that, with warm shadows cast from warm light. The quality looks very nice.
Technical Art
Polycounts are a bit on the high side for such scene; I believe the scene could look almost the same with halved polycounts. You could also consider using trims, tileable materials and reusing the same texture space for different pillars and bridge planks to get the most out of your textures space, even if the end results do look spectacular even as they are now.
The lighting looks very nice.
Documentation
There are lots of nice reference images. The process is well written and shown with texts and images. I like the show of lineart approach.
Final Presentation
The diorama shots read very well and showcase the use of color very well. The renders are high resolution and show the subject matter in a nice fashion.