Located 670 kilometers southwest of Paris, Albi was built around the original cathedral of Saint Cecilia, the largest brick church in the world. Because the area did not have good quarry stone most of Albi's buildings are red brick made from the soil of the bed of the Tarn River, which flows through the heart of the city. Known as the "red city" Albi has been a thriving settlement since Roman times. A UNESCO World Heritage Site, the old city features architecture that dates back to the Middle Ages.