La Teste-de-Buch (; Occitan: La Tèsta de Bug ) is a commune in the Gironde department in Nouvelle-Aquitaine in southwestern France. It is located on the south shore of Arcachon Bay, lying in the southwestern part of Gironde. It is the largest of four communes that comprise the (COBAS), a small metropolitan area of 54,204 population (1999 census). It is the eighth-largest commune in metropolitan France in geographical area. La Teste-de-Buch is famous for the Dune du Pilat, the highest sand dune in Europe. It is also the site of a fictional battle during the Napoleonic wars depicted in Sharpe's Siege by Bernard Cornwell.
