Minarets

The minaret of the Great Mosque at Kairouan
A minaret was a tower that Islamic holy men called muezzins
climbed in order to call out the call to prayer, five times a day. It
was a tall thin building with stairs inside it (or sometimes outside) and small windows to let
in daylight. At the top, there was an opening for the muezzin (moo-EZZ-in)
to call out the prayers so everyone would know that it was time to pray.
Most minarets were near mosques, where men (though not women) came to pray.
The oldest minaret that is still standing is the one you see here from the Great Mosque at Kairouan, in North Africa, which was built during the 700's AD. Another early minaret is the one from the Great Mosque at Samarra, which was built in the 800's AD.
When the Almovarids ruled North Africa and Spain, they disapproved of minarets, and so people built mosques without minarets in those areas during the 1000's. But when the Almohads conquered the Almovarids, they built a lot of minarets to show that they had won.
Nobody knows how Christian bell-towers are related to Islamic minarets, but Christian bell-towers of the 800's and 900's AD looked very different from Romanesque bell-towers, and Romanesque bell-towers look a lot like minarets, so it's possible that the Romanesque builders got the idea from Islamic minarets.
