 Pau was a castelnau founded at an unknown date, in the second half of the 11th or the very beginning of the 12th century, to control a fording of the Gave de Pau which was used for the passage of the shepherds in transhumance between the mountains of Ossau and pasture of the plain of the Pont-Long.A castle was built, overlooking the north bank, at equal distance from Lescar, seat of the bishops, and from Morlaàs, capital of the Viscounts of Béarn.In 1188, Gaston VI assembled his "" there, predecessor of the "conseil souverain" and roughly equivalent to the House of lords.