This is real nature in Prague, nature conservation area Prokopské údolí (Prokop valley). It´s very close to civilization, so you can go by public transport to one side and run to the other side very easily.
Some recommended route from Stodůlky to Hlubočepy.
Here is one photo from me (sorry for quality - it´s from my phone during the run :-)) But as you can see there is really quiet and nice nature. Don´t worry, there are some people during the weekend (because of some childrens play places there), so it´s safely... I think.