As the first royal palace in Paris, the palace de la Cité had its hour of glory under the Capetian monarchs, especially Philippe le Bel, who in the 14th century enlarged and transformed the building to make it the most sumptuous royal palace in medieval Europe and a symbol of his power. The hall of guards at the Conciergerie dates from this period, as do the huge soldiers’ hall and the kitchen built by Jean le Bon.

In the reign of Charles V, at the end of the 14th century, French kings began to prefer the palaces at the Louvre and Vincennes to the Palais de la Cité. They thus entrusted the old palace to the keeping of the Concierge, an individual who had extensive legal and police authority. The cellars of the building, which had for all practical purposes become a courthouse, were made into a prison. This function was confirmed over the centuries, and in 1793, the Conciergerie became the main prison of the revolutionary law courts. — Centre des Monuments Nationaux