English: This mosaic of two astronaut photographs illustrates the closeness of Arequipa, Peru, to the 5,822-meter-high El Misti Volcano. The city centre of Arequipa, Peru, lies only 17 kilometres away from the summit of El Misti; the grey urban area is bordered by green agricultural fields (image left). Much of the building stone for Arequipa, known locally as sillar, is quarried from nearby pyroclastic flow deposits that are white. Arequipa is known as “the White City” because of the prevalence of this building material. The Chili River extends north-eastwards from the city centre and flows through a canyon (image right) between El Misti volcano and Nevado Chachani to the north.