Answer:
They travel to Mecca.
Step-by-step explanation:
It is located in Saudi Arabia and is considered as the holiest city for the Islam religion. The entrance to non-muslim is forbidden.
The pilgrimage to Mecca is known as Hajj, the Arabic word for "Pilgrimage". It is an annual trip to that city by all Muslims, it is mandatory for their religion and must be carried out at least one time in the lifetime of the Islamic people.
I hope this answer helps you.