What makes a building a mosque?

A mosque is a place of worship for Muslims, and it needs less than you might think. The word can mean a covered building, but it can also mean any place where Islamic prayers are performed, even an open courtyard. What makes the great mosques of the world look alike is a handful of features that grew up around one practical need: everyone must pray facing the same direction.

That direction is the qibla, the direction of the Kaaba in Mecca. According to Islamic tradition, the early community in Medina first faced Jerusalem, and later turned to face the Kaaba. In a mosque, the wall that faces Mecca is the qibla wall, and worshippers line up in rows parallel to it, so a whole crowd faces the same way. In the middle of that wall sits the mihrab, a niche that shows the direction. The earliest mihrabs were just a stripe of paint or a flat stone panel; the imam, who leads the prayer, stands at the front, and a niche saves space for him.

Beside the mihrab stands the minbar, a pulpit for the Friday sermon. Muhammad's own was a simple chair, and later ones became large and beautifully carved. Outside the prayer hall you often find a courtyard, called a sahn, with a fountain or pool for ritual washing, and a minaret, a tower from which the muezzin gives the call to prayer. Early mosques had no minarets at all: in Medina the call was given from a doorway or roof.

So a mosque is not defined by a dome or a tower. It is defined by orientation, with the other features gathered around it.