It is called one of two things : either a pilgrimage or hajj, with hajj being the more religious term.
Pilgrimage.
It is called pilgrimage (or hajj in Arabic)
In English, such people are on a pilgrimage, and they are called pilgrims.
A pilgrimage. It is called pilgrimage (or Hajj in Arabic, in the Islamic Context)
This journey is called a "pilgrimage" because it is a religious or spiritual journey undertaken by a person to a sacred place or shrine as an act of devotion, penance, or thanksgiving.
A journey to a sacred place is typically called a pilgrimage. In Islam, the Hajj or Pilgrimage to Mecca is a very beautiful thing were Muslims all over the world come to the Grand Masjid (Mosque)
Jerusalem (Al-Quds in Arabic) was and still is important to Islam because in Islam it is the place where Mohammed ascended to heaven.
In Jerusalem, the Temple Mount (Har Ha-Bayit or Haram Ash-Sharif) is sacred to both Judaism and Islam.
the prophet muhammad was born there and its a religious place for islam
Masjid al-Haram is called "haram" because the word "haram" in Arabic means sacred or forbidden. The mosque is considered the most sacred place in Islam, and certain actions are prohibited within its boundaries, hence the name "haram."
a journey to a sacred place
a long journey made to some sacred place, as an act of religious devotion