I think it is important for Muslims to have a holy building because then they will have there own place to worship God and to read they're prayers. Even some people stay to listen to speeches from famous Muslims which they sleep in the Mosque for.
It is Jerusalem
Mecca and Medina
The first and most important holy city is Makkah (or Mecca) in the Kingdom of Saudi Arabia.
Everybody thinks his holy book is important. Muslims are somewhat outstanding in this regard for the rules they have regarding the treatment of physical copies of their al-Qur'an almost amount to idolatry.
Muslims do not worship anything except Allah (or God in English and same God worshiped by Christians and Jews) as the one and only one God with no partner, no companion, no son, no father, no associate, and no equivalence.They believe in the Quran as God holy book as they believe also in other God holy books (the Bible and the Torah).The God holy House Kabba is the sacred building for Muslims.
Medina is important to us Muslims because it is the holy city of Prophet Muhammad (S.A.W)
Mecca and Jerusalem are holy cities for Muslims.
This is amazing archaeological building.People do not pray there or use this place for special things, this building is part of the Muslims mosque - El Aqza that very important to them .The reason this building is so popular because this is the symbol of the Palestinian nationality.
In other cultures the Holy Land is important in other ways. For example, the Romans thought the Holy Land was important because to them more land meant more power. To the Muslims, the Holy Land was important to their religion, but not for the same reson it is important to a Jew or Christian.
There is no holy river for Muslims or for Islam religion.
They fought because the Muslims had control of Jerusalem, the most important city to the Holy Roman Empire. To get Jerusalem back under the control of it, the crusaders started the Crusades, or holy wars.
Al Quds is important for both Jews and Muslims because there are there for Jews the holy places of the Western Wall and the Temple Mount Complex and for Muslims there are there Al-Aqsa mosque (that is considered the third of the three holiest mosques in Islam history). For both Muslims and Jews the whole site of Al-Quds (or East Jerusalem) is holy.