What is "fronsac"

Fronsac is the name or part of the name of the following communes in France:

• Fronsac, Gironde, in the Gironde department
• Fronsac, Haute-Garonne, in the Haute-Garonne department
• La Lande-de-Fronsac, in the Gironde department
• Saint-Genès-de-Fronsac, in the Gironde department
• Saint-Michel-de-Fronsac, in the Gironde department