Jerusalem is considered holy by all three religions.
Jerusalem, the holy city
Jerusalem
well, since three religions claim that they are the true religion, and the major holy city happens to be the same in all three religions, followers of each religion try to claim the city for their religion. they don't want to divide it up.
It is unclear what the "other" religions are from the perspective of this question. Please read the Related Question which discusses all three major religions that make claims to Jerusalem. All other religions are not affected by that city except tangentially through the three monotheisms.
The holy city claimed by all three major monotheistic religions (Christianity, Judaism, and Islam) is Jerusalem. It is a city of significant religious importance and holds key sites such as the Western Wall, the Church of the Holy Sepulchre, and the Dome of the Rock.
It's untrue to say that they're all polytheistic.
Considering that these three are religions, not geographic regions, they are not geographically similar. However, all of three of them see the city of Jerusalem as being a holy city.
They were all religious leaders founders of three religions.
All three monotheistic religions (Judaism, Christianity, and Islam) have important holy sites in Jerusalem.
Jerusalem
Christians, Jews and Muslims, in no particular order. These being the people of the book. Also it is respected by any faith which respects those above religions such as Bahai and devotees of the recently deceased Sai Baba, who embraced all religions. Hindus, Bhuddists, Animists and all the other major religions have no special regard for Jerusalem.