Arabic in which the holy Qur'an is written
The Quran, Muslims holy book, was revealed in Arabic by God to prophet Muhammad (PBUH).
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Very sacred to them
It is the city of Jerusalem. It is sacred city for Muslims, Christians, and Jews.
Islam is a universal religion. Its followers use different languages. However, the holy Qur'an, most sacred book of the Muslims, was revealed in Arabic.
the city of Jerusalem.
dik, their considered sacred
The Kaaba is the most sacred spot on earth for Muslims. The Kaaba is located in Mecca (or Makkah), in the Kingdom of Saudi Arabia. It is the most sacred city for Muslims for having Al-Masjid Al-Haram (or the Grand Mosque) that surrounds the Kaaba.
If by the Sacred Mosque you mean the Great Mosque in Mecca, yes it is.
No one specific color is ''sacred'', however the color most often associated with Muslims is green, because the Ottomans, who used it in their flag, were primarily Muslim.
Muslims don't worship any building. Even, the Kaaba (that is the most sacred Islamic building) is not worshiped by Muslims but respected and honored by Muslims. If you wish to read about places where Muslims worship (both houses of worship and sacred sites) read the Related Question below.