Pope Francis begins longest journey of his pontificate | What you need to know

Pope Francis began his 45th trip on Monday, the most ambitious of his pontificate, both in terms of distance and duration.

It is a 12-day odyssey, across four countries and two continents, with stops in Indonesia, Papua New Guinea, Timor-Leste and Singapore.

This is not his first trip to the region: at the beginning of his pontificate, he made four long trips, to South Korea, Sri Lanka, the Philippines and Japan. In recent years, he has also visited Bangladesh, Myanmar, Thailand and, last year, Mongolia.

The historic trip comes amid recent concerns about his health. The pope suffers from mobility issues and has been hospitalized several times for breathing problems.

As is his custom, he boarded the papal plane Monday in a wheelchair, using an elevator. He then used a cane to walk down the aisle to greet reporters, but appeared in good spirits. Francis will be 88 in just three months; it is the first time he has left Italy in nearly a year.

In Indonesia, the world’s most populous Muslim-majority country, the pope’s message will focus on interfaith dialogue and cultural plurality, according to the Vatican. Francis will deliver a speech at Jakarta’s famed Istiqlal Mosque, alongside Indonesia’s grand imam.

The Pope will then visit the “Tunnel of Brotherhood,” which connects the mosque to a nearby Catholic church. This underground tunnel was recently built as a symbol of religious harmony.

On the eve of his departure, Pope Francis called for a “concrete commitment” to combat climate change. The pope will also travel to more remote areas of the country to meet with missionaries. Other themes of the trip include social and technological development, as well as the environment and the need to combat climate change, according to Vatican spokesman Matteo Bruni.

In Papua New Guinea, one of the poorest countries in the world, Pope Francis will stop in Port Moresby, one of the most dangerous cities in the world.

The pope will then travel to Timor-Leste, Asia’s youngest country, where he will have to deal with the fallout from a new sex abuse scandal involving priests. The pope’s first visit to the country comes just two years after the Vatican sanctioned independence hero Bishop Carlos Ximenes for sexually abusing young boys.

In the deeply Catholic country, many have brushed off the accusations, choosing to continue celebrating the Nobel Peace Prize winner as a figure who saved lives during the country’s bloody struggle for independence. It is unclear whether Pope Francis will address the issue or meet with some of the victims, as he has done in the past in other countries.

And in Singapore, the Pope will again focus on how different religions can live in harmony.

“Pope Francis will meet in particular with young people engaged in interreligious dialogue, entrusting them with the future of this path, so that they may become the protagonists of a more fraternal and peaceful world,” Cardinal Piero Parolin told Vatican media.

His trip to Singapore is also seen as an attempt to improve relations with China, a constant diplomatic initiative of the Vatican in recent years, in the hope of improving the situation of Catholics in China. The pope has previously said he dreams of visiting the country. Three-quarters of the population of the city-state of Singapore are ethnic Chinese, and Mandarin is one of the four official languages.