Valle del Arcoiris sits about an hour from San Pedro de Atacama, along a desert road that opens onto a landscape streaked with colour. Iron, copper and volcanic ash give the rock its palette: deep reds, ochre, green and pale gold, changing shade as the sun moves. You walk through it at your own pace, with a guide who knows the geology and the silence. Hierbas Buenas, nearby, holds pre-Columbian petroglyphs carved into dark volcanic stone: figures, animals, and patterns left by the people who crossed this desert long before the road existed. The combination of colour, quiet and deep time is what makes this excursion stay with you.