This coloring page depicts the martyrdom of St. Peter. According to ancient and well-known tradition, Peter, when he was condemned to death in Rome, requested to be crucified upside-down because he did not believe that a man is worthy to be killed in the same manner as Jesus Christ.
"But now it is time for thee, Peter, to deliver up thy body unto them that take it. Receive it then, ye unto whom it belongeth. I beseech you the executioners, crucify me thus, with the head downward and not otherwise: and the reason wherefore, I will tell unto them that hear" – Acts of Peter