On what does the Pope wear his "campagi"?

A "campagi" is the footwear of the Pope and the Clergy that he and they wear on their feet.

In ancient times a "campagi" could have resembled modern sandals but were actually marching boots. Likewise in ancient Roman, sandals proper were not worn outside by the Romans, rather they were regarded as indoor footwear, sometimes even carried by Roman slaves to be changed into for such things as banquets.

On the other hand, a "campagi", can also be the heavy-soled hob-nailed military boots known for being issued to Roman legionary soldiers and auxiliaries throughout the Roman Republic and Empire.