MADRID, June 7, 2026 (BSS/AFP) - Pope Leo XIV will celebrate an open-air mass Sunday in Madrid that is expected to gather more than one million worshippers in a highlight of his week-long trip to Spain.

King Felipe VI and Queen Letizia will join throngs of devotees in hot conditions at the emblematic Cibeles Square on day two of the first state visit by a pontiff to Spain since 2010.

Authorities have prepared a huge logistical and security operation, including a stage, seven giant screens, 608 loudspeakers, 2,300 toilets, 10 water points and more than 8,000 fences.

Leo will then lead a procession from Cibeles for hundreds of metres up to the famed Gran Via commercial thoroughfare and back.

More than 30,000 mostly yellow and white carnations -- matching the colours of the Vatican flag -- will adorn the procession's route in an elaborate floral carpet.

Crowds of excited believers -- including pilgrims from across Spain and beyond -- will likely line the streets of central Madrid for a second day to glimpse Leo on his popemobile after the ceremony.

- Call to stop polarisation -

The solemn ceremonies come as traditional religious observance has declined for decades in Spain, historically a deeply Catholic country, in line with much of Europe.

Later on Sunday, Leo will meet the leading lights of culture, sport and the economy at an arena, with the aim of fostering dialogue between faith and modern civil society.

On Saturday, 500,000 mostly young attendees congregated with Leo outside football club Real Madrid's Bernabeu stadium for a prayer vigil that stretched into the night.

Leo kicked off his visit with pomp and ceremony during a reception at Madrid's royal palace, where he urged society to put an end to "polarising narratives" and "sterile simplifications".

The pope also praised Spain, whose left-wing government has sparred with his native United States as well as Israel over wars in the Middle East, for its "active commitment to peace and solidarity among peoples".

Leo is due to visit Barcelona on Tuesday and Wednesday, where he will notably bless the Sagrada Familia basilica's recently completed tower, which made it the world's tallest church.

His trip will end with a focus on migration on Thursday and Friday in the Canary Islands, a key destination for irregular arrivals, with thousands dying in the Atlantic Ocean trying to reach them.