Taste the water by pili
Karlovy Vary has twelve mineral springs, each one with a different chemical composition, even different temperature. The one at the picture is the Sprudal, the oldest spring in use, right since the 13th century.This is also the largest and hottest of the springs (12m hight, 72 degrees celcius)
You can taste the water (the temperatures varies from 30-75 degrees). The water is free but it is a good idea to buy one of the special cups when you drink the water. The taste is very special and it is said to have a fantastic influence on the body.