Gedolim pictures are photos or sketches of (or attributed to) famous rabbis, known as gedolim admired by Jews.
It is a cultural phenomenon found largely in the Orthodox and Haredi Jewish communities. Gedolim pictures are pictures of famous rabbis and other prominent Jews which are circulated amongst the Jewish communities. Quite frequently, these pictures are posted on the walls of offices, businesses, houses, and schools where Jews are present.
Collecting Gedolim pictures has developed into a hobby for many Jewish children around the world; it is similar to collecting sports cards.
References
Gedolim pictures Wikipedia(Text) CC BY-SA