You've heard "Good King Wenceslaus" in the Christmas Carol. The song narrates a story of Wenceslas braving harsh winter conditions to provide aid to a poor peasant on the Feast of Saint Stephen, which is celebrated on December 26. It is based on the historical figure Wenceslaus I, Duke of Bohemia, who lived from approximately 907 to 935 AD. He is celebrated for his charitable acts and is regarded as a martyr and saint in the Christian tradition.
The tomb and relics of Saint Wenceslaus are here in Prague.
Here is one of many renditions of the carol "Good King Wenceslaus", this one by Bing Crosby.