The colonial centre of Arequipa was inscribed on the UNESCO World Heritage list in 2000 for its exceptional concentration of mestizo baroque architecture built from sillar — the local white volcanic stone. The protected zone is roughly the ten-by-ten block grid around the Plaza de Armas, extending north to Santa Catalina and the Rio Chili and south to the markets around San Camilo.
This is the part of the city where most visitors spend their time. Streets are narrow, sidewalks crowded, traffic chaotic — and the buildings themselves are at a uniformly two-storey height that makes the volcanoes loom at every junction. Stick to the area roughly bounded by the river, Calle Jerusalén, San Camilo market, and Calle La Merced. The further west or south you get, the more contemporary and less interesting the city becomes.