Having recently been to Vienna and Budapest I would advise travellers to use the underground going around these cities rather than walking unless it is for 15 minutes or less. The underground is very cheap in Vienna and in Budapest it is also cheap and is free for over 65`s when you show your passport. You can maxamise your time and avoid blisters on your feet! In prague places of interst are close together and there is not too much walking required.

I totally agree! The underground in both Vienna and Budapest is a lifesaver super cheap and efficient. Plus, walking too much can really wear you out, especially with so much to see.