Although the missions were considered temporary ventures by the Spanish hierarchy, the development of an individual settlement was not simply a matter of "priestly whim." The founding of a mission followed longstanding rules and procedures; the paperwork involved required months, sometimes years of correspondence, and demanded the attention of virtually every level of the bureaucracy. Once empowered to erect a mission in a given area, the men assigned to it chose a specific site that featured a good water supply, plenty of wood for fires and building material, and ample fields for grazing herds and raising crops. The padres blessed the site, and with the aid of their military escort fashioned temporary shelters out of tree limbs or driven stakes, roofed with thatch or reeds. It was these simple huts that would ultimately give way to the stone and adobe buildings which exist to this day.