Fortifications are militaryconstructions or buildings designed for the defense of territories in warfare, and also used to solidify rule in a region during peace time. Humans have constructed defensive works for many thousands of years, in a variety of increasingly complex designs. The term is derived from the Latinfortis ("strong") and facere ("to make").
From very early history to modern times, walls have been a necessity for cities to survive in an ever changing world of invasion and conquest. Some settlements in the Indus Valley Civilization were the first small cities to be fortified. In ancient Greece, large stone walls had been built in Mycenaean Greece, such as the ancient site of Mycenae (famous for the huge stone blocks of its 'cyclopean' walls). A Greek Phrourion was a fortified collection of buildings used as a military garrison, and is the equivalent of the Romancastellum or Englishfortress. These construction mainly served the purpose of a watch tower, to guard certain roads, passes, and lands that might threaten the kingdom. Though smaller than a real fortress, they acted as a border guard rather than a real strongpoint to watch and maintain the border.