pontifex

"Looking forward to the visit of @pontifex," Orban said on Twitter on Thursday evening.

The world's richest person tweeted a picture where he can be seen standing next to the pope, captioning it: "Honored to meet @pontifex yesterday."

In an accompanying @pontifex Twitter post, Francis said he was "beginning a new journey" on the service in order "to walk with you along the path of mercy and the tenderness of God."

He was the first pope to take his message regularly to Twitter, and the @pontifex account, first opened by Pope Benedict, now has 8.4 million followers.

In Rome, the pontifex maximus — an office held by Caesar — was the head of Roman state religion.