Over 120,000 people gathered in St. Peter's Square to witness the proclamation of Mother Teresa as a saint. Pope Francis officially proclaimed the Roman Catholic non as a saint.

On Sunday, Sept. 4, Pope Francis held a mass, and he officially canonized Mother Teresa as a saint at Vatican, according to The Wall Street Journal. The Roman Catholic nun is one of the most widely admired public figures in recent history.

During the canonization, Pope presented Mother Teresa's opposition to abortion. The Pope also acknowledged the dedication to the poor as facets of a single mission.

Despite the hot weather, the crowd of 120,000 gathered to witness the declaration in St. Peter's Square. There's a banner-size portrait of Mother Teresa hung behind the pope. The portrait is one of the late 20th century's most recognizable faces.

"Blessed Teresa of Calcutta to be a saint," Pope Francis declared.

During the vigil canonization, British artist Rita Ora performed "What Child Is This?"

In 2001, India renamed the city of of Calcutta to Kolkata to match the Bengali pronunciation, however, the church spells Calcutta referencing to Mother Teresa.

To some people, Mother Teresa was already a saint. Some people said, the Albanian-born nun lived in wonderful life, and some said she has the qualities to be a saint.

Before declaring the person as saint, The Vatican decided to do an official process, which includes an investigation.

The declaration mean to Vatican is that person, is in heaven and he/she can see God in heaven directly, according to CNN.

Mother Teresa was born Anjezë Gonxhe Bojaxhiu on August 26, 1910. When she was alive, she came in India in 1929 as a sister of the Loreto order.

During her stay in India, she set up her Missionaries of Charity in the slums of Kolkata in 1950 to help the poor. She died in Kolkata in 1997 at age 87.