Many people like to take a walk there, and many use it for jogging: the Botanical Gardens of the University of Vienna.
What I love so much about that place is that they do not only grow exotic plants there but also those which grow in and around Vienna. And they all have a nameplate saying which species they are.
Thus, this is an excellent place to try and get to know plants which are rare out there in the wilderness.
Here's one which is very simmilar to the sunroses growing in Lobau, but still slightly different - Helianthemum nummularium subsp. grandiflorum; it is different in two ways - it only grows in Alpine regions, and it has more hair.
