A flag flies over an entrance to the former Swiss artillery fortress Sasso da Pigna at the St. Gotthard mountain pass, Switzerland September 2, 2015. Sasso da Pigna fortress, located at 2,106 m (6,909 ft) altitude on the St. Gotthard mountain pass, was built from 1941 to 1945 and remained in military use until 1999. (Photo by Arnd Wiegmann/Reuters)
