You can follow the main street in front of the Municipal House towards the river - there are some big shopping malls along the way. Once you're on the river make a left and follow the river until you're back at the '''Charles Bridge''',
Or you can zig-zag through the old town. If you can keep your general bearing towards the west, you'll always eventually wind up at the river, turn left until you see the Charles bridge - you can't really get lost.
==== Mala Strana ("Little Side") ====