Why it looks like this

Sanaa, at about 2,300 metres in the Yemeni highlands, claims to be among the oldest cities on Earth. Its walled old town is unlike anywhere else: thousands of tower houses of rammed earth and burnt brick, their white gypsum window-tracery glowing against brown walls, standing shoulder to shoulder along narrow lanes.

Between the towers hide the maqashim — walled market gardens that fed the quarters — so the dense maze contains secret green rooms. UNESCO listed the old city in 1986; war since 2015 has put its ancient fabric at risk.