Since olden times there has been a weathercock on the back roof of the cathedral. It is said to serve as protection from the devil, who can carry out his evil deeds only until the cock's first crow. The following legend is associated with the weathercock on Saint Stephen's Cathedral:
Young Knight Kaspar von Schlezer was to carry a secret message to the Sultan in Constantinople.
Sadly he took leave from his beautiful young wife, who -- at their last farewell -- placed a silver crucifix around her beloved husband's neck to protect him from danger. He then set forth on the long and difficult route to Turkey. After a long journey Herr von Schlezer arrived safely at the Sultan's residence and delivered the secret parchment. Then he set forth toward home.
The knight's ship was attacked by pirates. They fettered him and at the next port sold him to a rich sheik. For many years the prisoner had to do difficult labor as a slave. Only the silver crucifix that he kept hidden on his breast comforted him and gave him hope that he would one day regain his freedom.
In his homeland his wife mourned for her missing husband for five years, but finally she gave up hope of ever seeing him again and became engaged to her husband's friend. Even as she was making preparations for the wedding her husband had a strange dream:
His wife was standing before the altar in Saint Stephen's Cathedral in Vienna and was exchanging wedding vows with Knight von Merkenstein.
A soft voice whispered in the sleeping man's ear: "You still have time to prevent this marriage."
Bathed in sweat, the knight awoke. In desperation he cried aloud: "I must be in Vienna tomorrow, even if the devil takes me!"
Instantly the Evil One, astride a feathered mount, appeared and spoke: "This rooster will carry us to Vienna, but in return I must have your soul!"
Herr von Schlezer agreed, but only under the condition that if he could sleep through the entire flight, the Prince of Hell would have no power over his soul.
The devil and the knight climbed onto the rooster's back and took off through the air. Before putting himself into the Evil One's hands, the nobleman secretly took hold of the crucifix on his breast. Then he committed his soul into God's hands and fell fast asleep. With uncanny speed they crossed meadows and fields, seas and lakes.
As dawn approached, the Steffl [Saint Stephen's Cathedral] came into view. Filled with joy, the rooster let out a loud cock-a-doodle-doo, upon which Schlezer awoke. The devil had lost power over his victim. Cursing loudly, he cast the knight and the rooster into the Danube River. Then the Evil One, mad as a rabid fox, returned to Hell.
Two fishermen pulled the pair from the water. Thus the nobleman was able to prevent the marriage of his wife to Knight von Merkenstein. Filled with joy, they fell into one another's arms.
To thank the rooster, who had freed him from slavery and returned him to Vienna in time, the knight had an iron weathercock constructed and installed on the back roof ridge of Saint Stephen's Cathedral. It can be seen there even today, where it reminds us of a devil's ride in the middle ages.