Final answer:
Muslims travel to Mecca for the Hajj, which is a central religious pilgrimage in Islam taking place in the city where the Prophet Muhammad was born and where the Ka'aba is located.
Step-by-step explanation:
Muslims travel to the city of Mecca for Hajj. This pilgrimage is one of the Five Pillars of Islam and is a journey that every adult Muslim is expected to make at least once in their lifetime if they are physically and financially capable. The annual pilgrimage to Mecca, known as Hajj, takes place during the month of Dhu al-Hijja and gathers millions of Muslims from around the world. The focal point of Hajj is the Ka'aba, a cube-shaped building within the Al-Haram Mosque in Mecca, which is considered the most sacred site in Islam.
During the Hajj, pilgrims undertake a series of religious rites including circling the Ka'aba seven times, running between the hills of Safa and Marwah, and participating in a symbolic stoning of the devil, among others. The city of Mecca holds great significance in Islam as the birthplace of the Prophet Muhammad and the site where Muhammad cleansed the Ka'aba of idols, restoring the monotheistic worship established by Ibrahim (Abraham).