Somali architecture is a rich and diverse tradition of engineering and designing. It involves multiple different construction types, such as <answer>stone</answer> cities, castles, citadels, fortresses, mosques, mausoleums, towers, tombs, tumuli, cairns, megaliths, menhirs, stelae, dolmens, <answer>stone</answer> circles, monuments, temples, enclosures, cisterns, aqueducts, and lighthouses. Spanning the ancient, medieval and early modern periods in Greater Somalia, it also includes the fusion of Somalo-Islamic architecture with Western designs in contemporary times.
What material was used to make Somali cities?
stone