Petra's monuments we have come up empty. If there ever was decorated interior (and some remains are to believe that it was), now what we see upon entering the Treasury is the clean mountain stone, a stone with streaks of natural colors, a huge canvas on which painted nature harmoniously. I walk through the valley in which, from the fourth century BC, the Nabataeans built their capital, when it comes to me the sound of a song. It comes from the inside of one of the Royal Tombs flanking the main avenue. I climb up there. A Jordanian police beats the boredom of long hours of guard singing a beautiful melody. His voice echoed in the empty stone walls composing for a unique soundtrack that surely did not enjoy the Swiss explorer Jean-Louis Burckhardt as the best kept secret rediscovered by the Arabs of the Middle East.