Les Baux-de-Provence sits in the Alpilles mountains, atop a rocky outcrop that is crowned with a ruined castle overlooking the plains to the south. Its name refers to its site: in Provençal, bauç is a rocky spur; bauxite was coined for aluminum ore when first discovered there by geologist Pierre Berthier in 1821. The village is considered one of the most beautiful in France and although it welcomes over 1.5 million visitors per year, it has only 22 residents in the upper part of the commune. The defensive capabilities of Baux have always made it an attractive location for human habitation, and traces of habitation date to 6000 BC. The site was used by the Celts as a fort around the 2nd century BC, and from the end of the 2nd and early 1st centuries BC limestone was extracted from quarries around Baux and the locals began to build durable houses. The process of permanent construction was parallel with the growth of trade with Mediterranean traders. In exchange for luxury goods, the inhabitants of the Alpilles produced grain, and achieved economic independence at the same time that the Greek colony at Arles attracted many people from across the region. In the Middle Ages the area became the stronghold of a feudal domain covering 79 towns and villages. The fortress was built from the 11th century, and the princes of Baux controlled Provence and gained a formidable reputation. They were said to be descended from the Biblical Magi Balthazar and their coat of arms was a silver star with sixteen branches as a reminder that, according to the Gospel, it guided the three wise men to Bethlehem.