Final answer:
Christians were rounded up and tortured in various locations throughout the Roman Empire during the period of Christian persecution. The persecution was carried out by the Roman emperors, most notably during the Great Persecution under Diocletian. These options are not applicable.
Step-by-step explanation:
Christians were rounded up and tortured in various locations during the Roman Empire's persecution of Christians. The most widespread official persecution took place during the Great Persecution, carried out by Diocletian beginning in 303.
Christians were arrested, tortured, mutilated, burned, starved, and even condemned to gladiatorial contests for entertainment. The persecution of Christians was not limited to a specific location such as the Circus Maximus, Colosseum, Pantheon, or Vatican City, but occurred throughout the Roman Empire.