The ALICE (A Large Ion Collider Experiment) high momentum particle identification (HMPID) detector, presently under construction, consists of seven identical proximity focusing ring imaging Cherenkov (RICH) counters exploiting large area CsI photocathodes for Cherenkov light imaging. With a total area of 11 m(2), it represents the largest CsI-RICH system ever used in High Energy Physics. The detector layout, assembly and quality checks will be presented, with particular emphasis on CsI photocathodes mass production. A validation procedure has been established combining the results of the photocathode response mapping obtained in a dedicated VUV scanner with test beam data. The long-term stability has also been studied by irradiation with a Sr-90 source of a final size CsI photocathode inside a detector prototype.