Shaykh Abdul Azeez ibn Baaz rahimahullaah was asked in his Majmoo` Fataawaa vol. 14, page 297:

Q: Is it allowed to use zakat (Obligatory Charity) money for the purpose of building mosques; due to the saying of Allaah: “And in the Cause of Allaah” (9:60)?

A: What is correct is the the intent of His Saying – He, the Most High: “And in the Cause of Allaah” (9:60) – according to the people of knowledge is: they are those who go out to fight, and Jihad (legitimate Islamic warfare) for the sake of Allaah.

So it (zakat) is not to be used for mosques, nor schools – according to the majority of the people of knowledge.

Some of the people of later times held the opinion that it (zakat) is permissible to be spent upon charitable projects – however this is a weak saying; because it contradicts that which the evidences indicate, and it contradicts that which the people of knowledge of the past were upon.