Answer:
It is largely because of Mecca and Medina, which are deemed to be sacred cities, cherished by a billion Muslims across the globe. Mecca is home of the Kaabah situated in Masjidul Haram. It is a cubical building, which was initially built by Prophet Ibrahim, and his son, Ismaeel.
Step-by-step explanation:
It is the holiest of Muslim cities. Muhammad, the founder of Islam, was born in Mecca, and it is toward this religious centre that Muslims turn five times daily in prayer (see qiblah). All devout and able Muslims attempt a hajj (pilgrimage) to Mecca at least once in their lifetime.