Standard diplomatic protocol calls for political and religious leaders to exchange gifts when visiting one another, and a papal trip to the Holy Land is no different.
When Pope Paul VI met in Jerusalem with the spiritual leader of the world's Orthodox Christians in 1964 - an encounter Francis is commemorating with his visit - Paul presented Patriarch Athenagoras with a chalice, while the patriarch gave Paul a golden medallion which Orthodox bishops wear. The significance was immediately clear: a mutual desire to end 900 years of division stemming from the Great Schism of 1054, which split Christianity into Catholic and Orthodox churches.
"The chalice was a symbol of sacramental union ... while the medallion was a sign of episcopal unity," said Valeria Martano, whose recent book "The Embrace of Jerusalem" recounts the historic meeting.
Political points can also be scored with gifts: When Israeli Prime Minister Benjamin Netanyahu visited Francis in December, he gave him a book about the Catholic Church's forced conversion of Jews in Spain written by his late father, an expert on the Inquisition. When the Palestinian leader, Mahmoud Abbas, paid his respects a few months earlier, Francis presented him with a pen. "I hope to use this pen to sign a peace accord with Israel," Abbas said.
To watch for then is what Francis will give, but more importantly what he'll receive from his various hosts.
In the West Bank city of Bethlehem, Palestinians plan to give the pope a cross that includes pieces of the Israeli separation barrier that surrounds the biblical town. A local artist, Nicola Elias, will give the pope a painting showing Francis carrying a cross near the barrier. Palestinians say the barrier - which Israel says is a security measure - has hindered movement and suffocated the economy.
In Jerusalem, meanwhile, Israel's national Holocaust memorial, Yad Vashem, is preparing to present the pope a number of items, including a collection of poems and a replica of a painting made by Abraham Kolowicz, a 14-year-old boy who perished in the Auschwitz concentration camp.
The gifts are part of a larger battle between Israel and the Palestinians to win support for their deep connections to this contested piece of land.
For Israel, the pope will visit the Western Wall, the holiest site where Jews can pray, and the Yad Vashem Holocaust memorial. For Palestinians, the pope will go to a Palestinian refugee camp and the Dome of the Rock in Jerusalem's Old City. Each stop carries great significance. Israel wants the pope to see the ancient Jewish connection to the Holy Land, and to appreciate the great Jewish suffering that took place in the Holocaust. Palestinian refugees will tell the pope the story of the great suffering they have experienced in the 66 years since Israel was founded, while the Dome of the Rock symbolizes the Palestinian connection to east Jerusalem, which they claim as a future capital.
In Jordan, the first leg of Francis' trip, the pope will also make two symbolically significant stops: Praying at the spot where Jesus is believed to have been baptized, and meeting with Syrian, Palestinian and Iraqi refugees, learning first-hand about the plight of Christians fleeing conflict in the region.
To watch for is the text of the note left by Francis at the Western Wall. When St. John Paul II visited in 2000, he left a note asking forgiveness for the suffering inflicted on Jews by Christians over history. Pope Benedict XVI's note prayed for peace for Christians, Muslims and Jews alike. The Vatican hasn't said whether Francis' note will be made public.
Vandalism and security concerns
In recent weeks, vandals believed to be fringe Jewish radicals have scribbled anti-Arab and anti-Christian graffiti on Christian holy sites, including an attack on the Vatican's own Notre Dame Center in Jerusalem. The hate crimes have angered local church officials. Israeli authorities say they are working overtime to prevent any embarrassing incidents during the pope's stay.
The arrival of a pope to one of the world's most volatile conflict zones has created all sorts of challenges for local authorities - especially given Francis' aversion to heavy security and armored cars typically favored by world leaders. Francis plans to use his open-topped car for spins through Amman's stadium, where he will celebrate Mass on Saturday, and then again in Bethlehem on Sunday. He'll use a regular car for other transportation.
Adnan Dameri, spokesman for Palestinian security, said thousands of police from across the West Bank will be deployed to keep order.
"The pope is a man of the people and will let people get close to him and greet him. Therefore we have developed a security plan on this background assuming that he will be surrounded by people," Dameri said. He said the Palestinians "have no concerns" and that the pope will be warmly welcomed in the overwhelmingly Muslim West Bank. Still, he said a number of roads would be closed to traffic beginning Saturday night.
In security-obsessed Israel, police spokesman Micky Rosenfeld said police will take "all necessary steps" to maintain security, including escorts and cordoning off of areas. Some 8,000 police are being deployed throughout Jerusalem, including undercover and intelligence units, with helicopter units flying overhead. There are more than 320 security cameras in the Old City alone.
To watch then is whether the security measures will enable the pope to do what he loves - plunge into crowds to greet well-wishers - while still keeping him safe.
Who sits where in the holy sepulcher?
There is perhaps no other piece of real estate on Earth that symbolizes the divisions in Christianity better than the Church of the Holy Sepulcher, where the faithful believe Jesus was crucified, buried and resurrected. Three main Christian communities - Greek-Orthodox, Armenian and Roman Catholic - share the church, zealously protecting their invisible turf borders and scheduling individual prayer services. Given that fist-fights among them occasionally break out, the joint prayer service planned for Sunday night will be a delicate exercise in religious protocol and diplomacy.
Francis and the spiritual leader of the world's Orthodox Christians, Ecumenical Patriarch Bartholomew I of Constantinople, will visit the church together and be greeted by the leaders of each of the three communities, and then all of them will pray together.
To watch for is how the event unfolds: Who sits where, who processes in first, who speaks and who doesn't will all carry enormous symbolic weight.
The Vatican has said Francis and Bartholomew will enter the church from two different entrances. But they will leave together in the same car and dine together at the Latin Patriarchate "to celebrate this extraordinary moment," said the Vatican spokesman, the Rev. Federico Lombardi.
One point of tension between Israel and the Vatican has been over Christian access to the Room of the Last Supper, where Jesus was said to have had his final meal with his disciples before being crucified. Israel controls the site, and the Vatican has long sought increased access for prayer. Israeli and Church officials say that they are close to a deal allowing increased Christian prayer at the site.
This has sparked rumors that Israel is going to turn over the site to the Vatican - a claim that Israel denies. Even so, ultra-Orthodox nationalist Jews have plastered Jerusalem with posters furiously claiming Israel will give the Vatican control at the site, whose ground floor is revered by Jews as the tomb of the biblical King David.
Israel generally prohibits celebrating Mass there and restricts Catholic prayers to twice a year, on Holy Thursday and Pentecost. It has refused greater access, wary of setting a precedent of relinquishing properties taken over in the 1948 war that followed Israeli independence.
Still, Israel is allowing Francis to celebrate a small, private Mass in the room though the Vatican has said no live television footage of the Mass is expected. St. John Paul II celebrated Mass in the room when he visited the Holy Land in 2000 and Benedict prayed in the room on his 2009 pilgrimage.
To watch then is whether the Mass is disrupted or marred in any way by protests - and if a deal granting Christians greater access is announced.