Relatives of some of the 218 people killed by the blast held up photos of their loved ones on Tuesday as Leo arrived at the scorched site.
They then stood side-by-side as he greeted each one in a line: Leo grasped their hands, spoke to each one and looked at the photos.
The emotional encounter took place next to the shell of the last grain silo standing at the site destroyed by the August 4, 2020 blast and the piles of burned cars torched in its wake.
The explosion did billions of dollars in damage as hundreds of tons of ammonium nitrate detonated in a warehouse.
Five years on, these families are still seeking justice.
No official has been convicted in a judicial investigation that has been repeatedly obstructed, angering Lebanese for whom the blast was just the latest evidence of impunity after decades of corruption and financial crimes.
"The visit clearly sends the message that the explosion was a crime," said Cecile Roukoz, whose brother Joseph Roukoz was killed and who was on hand to meet the pope.
"There should be a message, the country should end impunity and ensure justice is served."
When he arrived in Lebanon on Sunday, Leo urged the country's political leaders to pursue the truth as a means of peace and reconciliation.
The American pope opened his final day in Lebanon with an emotional visit to the De La Croix hospital, which specialises in care for people with psychological problems.
Awaiting him were some familiar-looking faces: young boys dressed up as Swiss Guards and cardinals, and even one dressed as the pope himself in all white.
The mother superior of the congregation that runs the hospital, Mother Marie Makhlouf, was overcome as she welcomed the Pope, telling him her hospital cared for the "forgotten souls, burdened by their loneliness".
Leo said the facility stood as a reminder to all of humanity.
"We cannot forget those who are most fragile. We cannot conceive of a society that races ahead at full speed clinging to the false myths of wellbeing, while at the same time ignoring so many situations of poverty and vulnerability," he said.
Leo was set to end his visit with a mass at another location along the Beirut waterfront, where he looped through the crowd in his covered popemobile.
Thousands of Lebanese flocked to the mass site and along his motorcade route, overjoyed that a pope had finally managed to visit.
Pope Francis had tried for years to come but was stymied first by its economic and political crises, and then by his own health problems.
Leo has sought to bring a message of peace to Lebanon as it copes with the economic crises, the aftermath of Hezbollah's devastating war with Israel and the fallout from the port blast.
