Pope Leo visited Istanbul's famed Blue Mosque on Saturday, removing his shoes in a sign of respect but not appearing to pray in his first visit as leader of the Catholic Church to a Muslim place of worship during his four-day visit to Turkey.

The first US pope bowed slightly before entering the mosque and was led on a tour of the expansive complex, able to hold 10,000 worshippers, by its imam and the mufti of Istanbul.

Leo, walking in white socks, smiled during the 20-minute visit and joked with one of his guides, the mosque's lead muezzin - the official who leads the daily calls to prayer.

Leo's first trip as pope being closely watched

As the group was leaving the building, the pope noticed he was being guided out a door that is usually an entryway, where a sign says, "No exit."

"It says no exit," Leo said, smiling. Askin Musa Tunca, the muezzin, responded: "You don't have to go out, you can stay here."

The pope is visiting Turkey until Sunday on his first overseas trip as pontiff, which also includes a visit to Lebanon.

Leo, a relative unknown on the world stage before becoming pope in May, is being closely watched as he makes his first speeches overseas and interacts for the first time with people outside mainly Catholic Italy.

Tunca told journalists after the mosque visit that he asked Leo during the tour if he wished to pray for a moment, but the pope said he preferred to just visit the mosque.

The Vatican said in a statement that Leo undertook the tour "in a spirit of reflection and listening, with deep respect for the place and for the faith of those who gather there in prayer."

The Blue Mosque is officially named for Sultan Ahmed I, leader of the Ottoman Empire from 1603 to 1617, who oversaw its construction. It is decorated with thousands of blue ceramic tiles, the basis of its popular name.

No visit to Hagia Sophia

The 17th-century structure is located across from the Hagia Sophia, a former Byzantine-era cathedral that Leo did not visit, in a break from past papal trips to Turkey. The Hagia Sophia, one of Christianity's most important places of worship for about a millennium, was made a mosque for 500 years after the fall of the Byzantine Empire.

It was converted to a museum by Turkey's secular republic more than 70 years ago but turned back into a mosque by President Tayyip Erdogan in 2020.

The Vatican has not commented on Leo's decision not to visit the Hagia Sophia. The late Pope Francis, who visited the structure during a 2014 trip to Turkey, said in 2020 that he was "very pained" that it had been made a mosque again.

Leo chose mainly Muslim Turkey as his first overseas destination to mark the 1,700th anniversary of a landmark early Church council there that produced the Nicene Creed, still used by most of the world's Christians today.

At a ceremony on Friday to commemorate the Church council with Christian leaders from across the Middle East, the pope condemned violence in the name of religion and urged Christians to overcome centuries of heated divisions.

Speaking to senior clerics from countries including Turkey, Egypt, Syria and Israel, Leo called it a scandal that the world's 2.6 billion Christians were not more united.