This area is on the waterfront on the Mala Strana-side of the Charles Bridge.  There are restaurants behind us (including Pub II) and restaurants on the other side of the bridge, through the arch.

During the floods of 2002 (14 June), this area was underwater.  On the wall next to the arch there is a brass plaque (it's nearly dead-center in this image and hard to see -- click it) which indicates the high-water mark.