Archaeology
The significance of the remains of a man crucified in Palestine in the 1st century has been interpreted in different ways, and in any case does not prove that Jesus was executed in the same way.
The Alexamenos graffito, which is the earliest surviving pictorial representation of a crucifixion and has been interpreted as mockery of a Christian, shows a cross as an instrument of execution. Its date is uncertain: some have posited for it a date as early as 85, but it may be as late as the 3rd century, and even thus prior to AD 300.
Read more about this topic: Instrument Of Jesus' Crucifixion