During the pre-industrial technological era the natural sources of energy were intensively exploited in Greece for the operation of water- and wind- powered installations, most of which were grinding mills. The watermills, which were mainly furnished with horizontal water wheels, were erected throughout the country, even on the islands, where there has always been a shortage of running water, while the windmills were primarily built in the Aegean, where suitable winds blow. In addition, water power was used for the operation of fulling-mills, water saws, oil mills and fulling-tabs, while wind power was employed not only for water pumping but mainly for the common Mediterranean tower mill and other types of mills, such as the horseshoe-shaped mill, which operated with a single wind direction, or the mill with a horizontally rotating propeller. In spite of the important cultural, historic, social and economic role these installations have played, it does not exist in Greece even to date, when they have been ruined by time, an articulated stet policy for their protection and preservation, although they are significant examples of pre-industrial technology and interesting monuments for archaeological and ethnological study.