This district was once considered the Mexican-American side of Tucson. It has been called Barrio Viejo or Barrio Libre since its Mexican inhabitants were more or less free to follow their own laws in the old days. That has changed, but the area has preserved its distinctly Mexican flavor with flat-roofed adobe (mud-brick) houses and roofs made from saguaro ribs and packed dirt (providing great insulation in the extreme Tucson climate). Some of Tucson's oldest structures can be found here and many of them nicely restored. Since most have been converted into private homes or offices, your visit will have to be confined to the exteriors.