An impres­sive defence work from the 9th cen­tu­ry, it has 17 black tow­ers. As a bonus, it hosts an extreme­ly large medieval ”’Tapes­try of the Apoc­a­lypse”’, real­ly a spec­tac­u­lar set of tapes­tries which is arguably one of the very great­est art­works that has come down to us from the Mid­dle Ages.