I read somewhere it wasn't actually a cross but more of an upright stake.
That's the way, the Romans did it.
At the end of the first century B.C., the Romans adopted crucifixion as an official punishment for non-Romans for certain limited transgressions. Initially, it was employed not as a method of execution, but only as a punishment. Moreover, only slaves convicted of certain crimes were punished by crucifixion. During this early period, a wooden beam, known as a furca or patibulum was placed on the slave's neck and bound to his arms.
The first historical record of Crucifixion was about 519 BC when "Darius I, king of Persia, crucified 3,000 political opponents in Babylon" .
Generally, cruxifction has been an important method of capital punishment, particularly among the Persians, Seleucids, Carthaginians, and Romans from about the 6th century BC to the 4th century AD. Constantine the Great, the first Christian emperor, abolished it in the Roman Empire in AD 337, out of veneration for Jesus Christ, the most famous victim of crucifixion.