Note: This story is part of a special issue marking the 175th anniversary of the founding of the Archdiocese of Chicago.

When Pope John Paul II visited Chicago Oct. 4-6 in 1979, he did not come as a stranger.

He had come to this most Polish of American cities twice as Archbishop of Krakow — once on his own, as part of a tour of the United States in 1969, and once only three years earlier as part of a delegation of Polish bishops.

But his whirlwind visit of 37 hours on those crisp fall days was the only time John Paul II visited as pope, and Chicago-area residents turned out in droves. Media estimated that more than a million people turned out to watch his motorcade make its way from O’Hare International Airport to Holy Name Cathedral on the evening of Oct. 4. He was greeted by no less a luminary than Luciano Pavarotti singing “Ave Maria.” There, he reflected briefly on the name of the cathedral, noting, “It is in the name of Jesus that I come to you. Our service to the needy of the world is exercised in the name of Jesus. Repentance and forgiveness of sins are preached in his name.”

John Paul II had left Rome five days earlier, traveling first to Ireland for two days. From there, he flew to Boston and celebrated Mass Oct. 1 on Boston Common. The next day, he went to New York, where he addressed the United Nations and celebrated an evening Mass at Yankee Stadium. On Oct. 3, he left for Philadelphia, where he again celebrated Mass.

Before arriving in Chicago Oct. 4, he traveled from Philadelphia to Des Moines, and then from Des Moines to O’Hare.

Even after that grueling schedule and the opportunity to pray at Holy Name Cathedral, the still young and vigorous pope did not stop. Instead, after dinner with Cardinal John Cody at his residence, he made his way to St. Peter’s in the Loop, 110 W. Madison St., to address more than a thousand religious brothers.

The next morning, he was up and away from the cardinal’s residence before 7 a.m., traveling through the neighborhoods to Providence of God Church in Pilsen, a primarily Mexican neighborhood where about 75,000 people stood in the early-morning chill to greet the pope.

From there, the motorcade continued through the South Side to Five Holy Martyrs Parish, 44th and Richmond streets, where the pope was scheduled to celebrate an 8 a.m. outdoor Mass in his native language for Polish Catholics.

From the Mass, the pope continued his journey through the neighborhoods of Chicago, arriving at Quigley Preparatory Seminary South, 7740 S. Western, now the site of St. Rita of Cascia High School.

There, he met with 350 American bishops and prayed with them. He also stepped out to the parking lot to meet with the 1,192 young men who were in the archdiocesan seminary system at the time, and he greeted thousands more Catholics who congregated on the school’s front lawn before taking off by helicopter to go back to the cardinal’s residence. His appearance at Quigley South also included a special greeting for the sick.

The 3 p.m. Mass in Grant Park, where an estimated 1.2 million crowded in to worship, was the centerpiece of his visit to Chicago. There, Pope John Paul II emphasized themes of evangelization and unity.

“Different as you are, you have come to accept each other, at times imperfectly and even to the point of subjecting each other to various forms of discrimination,” the pope said, speaking of the different waves of immigration that formed American society. The church also must grow in unity, he said.

The best way to evangelize, the pope went on, is to love.

“Love is the force that opens hearts to the word of Jesus,” he said. “Love is the only driving force that impels us to share with our brothers and sisters all that we are and have.”

He capped off that day by attending a concert at Holy Name Cathedral, performed by the Chicago Symphony Orchestra under the direction of Sir Georg Solti, before leaving Chicago for the last leg of his trip, a two-day stop in Washington, D.C., before returning to Rome.

This article was originally published  Sept. 10, 2017, and it has been edited..