The Vltava River has its source among the dark conifers of the Bohemian Forest. It flows north through Prague and merges with the Labe (Elbe) River at Mělník, which is 25 miles north of Prague. During the 13th century the main river traffic was timber, brought downstream in the form of rafts. Until the 19th century the riverside remained a strictly functional area, the domain of dyers, tanners, slaughtermen, fishmongers and others whose trades required a reliable water supply.

At night Prague looks magnificent from the Charles Bridge (Karlüv most). The buildings are dramatically lit and there is a stillness on the bridge that gives the city a fairytale quality. The Charles Bridge is a pedestrian-only bridge lined with statues of important historical figures. Construction began in 1357 under the direction of King Charles IV, and it has survived mostly intact due to it's durability. Eggs and wine were mixed into the mortar that holds the sandstone blocks in place, which gives the bridge unusual strength.

The Vltava is subject to violent floods which destroyed bridges and embankments and shifted islands from one part of its bed to another. At the end of the 13th century the level of Old Town was laboriously raised about 6 feet to counter the constant flooding.