One of the most welcome sights that I can picture in my mind is when I am lucky enough to have found a drinking fountain.  There is not many other thoughts that can be so refreshing mentally.  The remembrance of a nice long cool drink can invigorate and sate one even without actually having the pleasure of actually taking the drink.  Of course, the actual reality of finding one of these and having the pleasure of a partaking is better than this but not by much.  Some of my fondest thoughts are when I was really thirsty on a really hot summer day and was lucky enough to find a gem like this!