The Wawel Dragon is legendary dragon known in Polish folklore who lived in a cave under the Wawel Hill in Kraków on the bank of the Vistula River. The oldest story was created in XIII century by Wincenty Kadłubek, a polish historian and Bishop of Kraków. It begins with the appearing of Wawel Dragon during the reign of King Krakus. The beast demanded weekly offerings of cattle, and if people failed to bring animals he would devour them instead. But king Krakus wanted to slain the dragon so he called on his two sons Krakus II and Lech. Yet they failed to kill it with brutal force so instead princes tried to trick him. Lech and Krakus found calfskin and stuffed it with smoldering sulfur gave it to the dragon to eat. The Wawel Dragon ate the decoy out of gluttony, started to breathe fire and suffocated.
After the victory the two brothers started to argue about who deserves the honor of slaying the beast and who will take all the glory. During the fight between princes the older one Lech murdered the younger Krakus and spread lies about his death. He told everyone that the dragon killed his brother, the people believed him and made him a new king. Fortunately after some time they learned that he was lying, banished him and named the city after the brave and innocent Krakus.
According to some of the historians the legend of the Wawel Dragon is a symbol of the presence of the Avars on Wawel hill in XVI century who were demanding tribute. On the other hand a group of swedish scientists theorized that the dragon really lived and was in fact a strain of an archosaur, an ancestor of a crocodiles and birds. Today a metal sculpture of the Wawel Dragon can be found in front of the dragon’s den in the Wawel Hill in Kraków and it is now the best known cave in Poland.
Source: https://en.wikipedia.org/wiki/Wawel_Dragon