Thanks Martin and Thomas,

I downloaded the map of hotspot and overlayed it onto a physical map of Vienna. Turns out most of the spots cluster. Then I went those places to find the hotspots. Found a few, all private. Most interesting was to note the city-space around the hotspots. Unis, shopping streets, various business centers mark the spots.

In any case, FYI for those who have lots of data to download. Find a good internet cafe, the hotspots (and Metronet) are too slow. I suggest the place I'm writing from now:

http://www.icworld.com

Address:
Hedwiggasse 4, 1020 Wien
10:00-21:00