Gap is the prefecture of the department of Hautes-Alpes, in the region of Provence-Alpes-Côte d'Azur, Southeastern France. In 2019, the comm…Gap is the prefecture of the department of Hautes-Alpes, in the region of Provence-Alpes-Côte d'Azur, Southeastern France. In 2019, the commune had a population of 40,631, making it the most populated city in Hautes-Alpes. At a height of 750 metres above sea level, to the south of the Écrins Massif, it is also France's highest prefecture.