Eternal Library - Environment Concept - UE5

I created this environment for a course with the theme "Under the Dome", while I initially planned at least create some still renders in Blender as a comparison between Blender and Unreal, with the release of Unreal Engine 5 I decided to try and use all of the new tools, which made a Blender version to much effort for the benefit.
The idea behind the project was to create a sort of heavenly archive big enough to house the life story of every person who ever lived. The part we're able to see houses about 150 million books, which thanks to Nanite could have all been 3D models, but I decided to save a bit of performance and opted for a Substance texture instead. The whole scene still contains well over 100 million triangles, which would have been impossible to do with UE4.
All assets were directly imported from Blender with the more detailed ones being at least 1 million tris. To save time on texturing no assets except for the bookshelves are UV unwrapped, using blended triplanar mapping instead. All textures except for the books are from Quixel Megascans.
I'm really impressed with how well Nanite and Lumen work in realtime, creating such a huge scene would have probably been a lot more work in Blender, because of all the optimisation it would take to get any sort of reasonable render time. I know that I really pushed Lumen to the limit with an indoor scene and by using a lot of small mesh lights, so the flickering is quite noticable in realtime, but rendering a cinematic in this environment on a single PC would have been essentially impossible in Blender.