Btw, I looked for mausoleums first - and then for neoclassical temples. There are many. 
Over the last weeks, I spent some time here and there to find out where this picture might have been taken: Images of newer times
It must have been taken from here: https://www.pinterest.es/pin/341007003022697481/ , or at least I couldn’t find it anywhere else apart from Pinterest. No matter what I searched for, I didn’t find anything similar. So I looked for parks at lakes, with mountains nearby… So far only in Japan. No success as of now.