Stefan, good going, but a comment if I may.
The rocks/ballast you used for the paths is out of scale - if you consider the scale of the doors etc, the path rocks used would be insurmountable boulders to anyone entering
Sorry, but perhaps the rock choice should be smaller grit 0 I know railway model ballast is available in smaller sizes. I would have used beach sand personally.
Otherwise, great stuff. Will it actually be visible in the completed model?