Pope Francis has ended his tour of the United States with an open-air mass in Philadelphia.

The 78-year-old pontiff spent 6-days on his first visit to the US, where he called for compassion for immigrants and justice for child sex abuse victims of the Catholic church.

He's also announced that the next World Meeting of Families will take place in Dublin in 2018, increasing speculation he may be planning a visit to Ireland.

An audience of hundreds of thousands heard Pope Francis deliver a message of hope for families: