The theme of this documentary is the research for a disappeared city, that has been hidden for centuries under the sand of Moroccan Sahara desert. This city was called Sigilmassa and was founded in 750 AD: it had a splendid life - it was indee called city of gold - but it disappeared from political geography around the XVI century, devastated by earthquakes and floods. The walls of the city, analized in the documentary, witness the high civilization of these people.