Known as the gate­way to the desert, Agadez, on the south­ern edge of the Sahara desert, devel­oped in the 15th&nbsp,and 16th&nbspcenturies when the Sul­tanate of A&iumlr was established&nbsp and Touareg tribes were seden­ta­rized in the city, respect­ing the bound­aries of old encamp­ments, which gave rise to a street pat­tern still in place today. The his­toric cen­tre of the city, an impor­tant cross­roads of the car­a­van trade, is divid­ed into 11 quar­ters with irreg­u­lar shapes. They con­tain numer­ous earth­en dwellings and a well-pre­served group of pala­tial and reli­gious build­ings includ­ing a 27m high&nbsp minaret made entire­ly of mud brick, the high­est such struc­ture in the world.&nbsp The site is marked by ances­tral cul­tur­al, com­mer­cial and hand­i­craft tra­di­tions still prac­ticed today and presents excep­tion­al and sophis­ti­cat­ed exam­ples of earth­en archi­tec­ture.