It seems to me, and most tourists judging by the crowds, that Prague centres around Charles Bridge; it's the first of the bridges over the Vitava river (1357), is cobbled and is now just for pedestrians. I did take a photo of the street at the end of it yesterday which looks busy - but take it from me that the bridge itself was heaving!
I wanted to see it quiet and enjoy it, so at 5am I pulled myself out of my pit and walked the 30 minutes to watch the sun rising. It was very quiet with a few photographers doing the same. The girl dressed in red in the blipfoto was with a photographer - I can see his thinking as she does set the scene!
I was back in the hotel room by 7am after an amble back from the Old Town; a case of packing and travelling home - should be back before midnight with luck - with all the cases I hope!