When was Simon Peter crucified?

A:Although tradition says that Simon Peter was crucified approximately 64 CE on the orders of Emperor Nero, it seems that this was unlikely to have been the case. In fact we do not know when or how Peter really died.

The first known mention of the execution of St. Peter was made by the second-century Pope Anicetus who, wishing to demonstrate that he spoke with the authority of Peter, reported that Peter had been beheaded in Rome. A century later, Origen changed this to say that Peter was sentenced to crucifixion but, feeling unworthy of being crucified like Jesus, asked to be crucified upside down.

Yet Clement of Rome, writing around 95 CE (1 Clement), spoke in general terms about the life and death of Peter but appears to have been unaware that he had even visited Rome and was certainly unaware that he had been executed in any way at all. We do not know when he died, but the most reasonable conclusion is that Peter probably died of natural causes.