Pope passed through St. Peter’s Square on Popemobile in front of huge crowd awhile ago. Went into the palace to change vestments.
Inaugural mass should begin very soon.
Actually, he went into St. Peter's Basilica to the sacristy to vest for Mass. Then went to the tomb of St. Peter, in St. Peter's Basilica, to pray with eastern Catholic patriarchs and the Orthodox Patriarch Bartholomew before the procession to St. Peter's Square where the Mass took place.
The Apostolic Palace is a different building in the Vatican.