Umar stood for simplicity and austerity. Consequently he did not believe in any large scale program of public works involving extravagance. Nevertheless as a consequence of the extension of the Muslim rule to distant lands, the undertaking of works of public utility became imperative. As Muslim conquests extended east and west, and more and more persons embraced Islam it became necessary to construct mosques. During the caliphate of Umar, as many as four thousand mosques were constructed. During the caliphate of Umar many new cities were founded. These included Kufa, Basra and Fustat. Umar issued instructions against the construction of double storied houses and palatial buildings. Many buildings were constructed for administrative purposes. Many cantonments were constructed at strategic places. Special stables were provided for cavalry.