The first day, had all the rough meshes sent to 3ds Max. Once there, I separated in layers to work better on each one of the props hiding the others faster and having them more organized. The first try I made was with the columns, where i made a sketch of the rock blocks pattern.
Then, I took the 3 different ones (although all were different in size) to work on uvs and high poly. I did a small chamfer on them to add that extra bump detail later on. I wanted to work with them 3 at same time, so they shared same UVs map and material.
Once I had UVs and High Poly made, I went to substance painter to create the material I'd use for all of the rock materials in the scene. I gave them a an Egyptian Sandstone look. Added a bit more of darker tonality in the concavities, and then saved the layers as a new Smart Material ready to apply on every prop needed. Then I exported the maps, to import them inside Unreal alongside with the mesh.
The columns prefab was made of 2 column parts and one column base, once I had them both I edited the prefab swapping the basic meshes with the new detailed ones. I still don't know why it happened, but when I exported in cms (and worked on same units in 3ds Max) when importing back to UE4 it didn't have the expected size. But I found fast enough I had to scale props to 2.55 in all directions.
Once done, I moved to other props, bigger ones, as the Gate pedestal, stairs and rocks on both sides. And it started to become alive! Next day will be about walls.