In those years the Mausoleum of Hadrian was built. He had a good personality and prohibited to use the possessions of the divine cult in other modes. He wrote some other rules for priests with the grave punishments for the overstepping. To him is attributed the choice of the date for the celebration of Easter, i.e. on the first Sunday after the March full moon. Pius I governed in the times of emperor Antonius Pius, very tollerant with the christians, there was found no documents proving the martyrdom of this pope.
Some historians think that the pope was assasinated.
He concentrated all his forces on the battle against the huge number of people bringing heresy to Rome. In 161 Marcus Aurelius became and emperor and the new phase of very hard persecutios began. This pope confirmed the date for the celebration of Easter. Probably he was not martyred. He was also the first bishop of Rome buried in the catacombs of St Callistus, but in 1604 pope Clement VIII made his rests trasfered in the chapel of the palazzo Altemps.