If you are journeying between Lima and the Altiplano at least 1 way by land (as you really should) then a stop over in Arequipa is certainly worthwhile both to break the journey and to take in this pleasant colonial town.
Its main claim to fame lies in the buildings, particularly the churches with their carved facades, built in the local white volcanic stone (photo).
Its climate is very fine with mostly clear sunny days, not too hot and providing wonderful views of the surrounding volcanoes – one of which “El Misti” is the archetypal volcanic conical shape. The Santa Catalina Convent is also worth a visit. (visited 1984)