Answer:
In mainland France, the three largest departements are in the "Aquitaine" region; they are from biggest down:
- Gironde (Bordeaux) (10 000 sq km)
- Landes (Mont de Marsan) (9 243 sq km)
- Dordogne (Périgueux) (9060 sq km)
outside mainland France, the largest departement is la Guyane (83 534 sq km),