Fortifications are militaryconstructions designed for defensivewarfare. They have been used for many thousands of years, in a variety of increasingly complex designs. The practice of improving an area's defense is also known as "fortification". Many military installations are known as forts, although they are not always "fortified".
... the North Pole
Auguste Piccard, (1884-1962), physicist and explorer
Jacques Piccard[?], (born 1922), undersea explorer
Francisco Pizarro, (1471-1541), conqueror of the ...