Pope Francis marked the beginning of the Jubilee of Mercy by opening the Holy Door at St. Peter's Basilica in the midst of the heightened security. The Jubilee of Mercy is considered as a special Holy Year for Catholics.

The Pope slowly walked through the doorway of the Holy door followed by Pope Benedict XVl, 88, whose resignation led to Pope Francis' tenure as Pope in 2013. According to USA Today, almost 10 million pilgrims are expected to pass through the Holy bronze door sealed within a 12-month period.

The Jubilee's purpose is to call all the Catholics to reflect on the theme of Mercy. Moreover, the Holy door will be opened for the first time during the Jubilee of Mercy at cathedrals all over the world starting this Sunday.

Five  thousand security officers are expected to be deployed in Rome to secure the safety of the people and the Pope. A no-fly zone policy has been imposed to protect the arriving pilgrims. Before the people could enter the Holy door, they had to pass through metal detectors to ensure a smooth ceremony.

The Pope, together with his colleagues, celebrated the special Mass in St. Peter's Square with over 50,000 people watching and attending the mass.

"You cannot conceive of a true Christian who is not merciful, just as you cannot conceive of God without his mercy. Mercy is the key word of the Gospel. ... We should not be afraid: We should allow ourselves to be embraced by the mercy of God, who waits for us and forgives everything," Pope Francis said as he led the crowd in prayer.

The Pope also asked the thousands of people to offer prayers for Benedict's good health. And the crowd cheered in response to what he asks. The last Jubilee was celebrated in 2000 with St. John Paul ll and the next Jubilee is expected to be celebrated on 2025.

The true essence of the Jubilee celebration focuses on when Catholics can have special indulgences and also ask forgiveness of their sins.