Somali architecture is a rich and diverse tradition of engineering and designing. It involves multiple different construction types, such as stone cities, castles, citadels, fortresses, mosques, mausoleums, towers, tombs, tumuli, cairns, megaliths, menhirs, stelae, dolmens, stone 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.