Thank you for submitting your item for appraisal. This appears to be a vintage reproduction of a photograph, showing Joseph Stalin, Winston Churchill and Franklin D. Roosevelt at the Tehran Conference. The photo in your possession appears to be a (smaler) photographic reproduction of another well known and widely publicized photo. https://texashistory.unt.edu/ark:/67531/metapth36534/m1/1/
This is not a rare item unfortunately, possibly part of an album about World War II. The estimate is based on similar vintage photos offered or sold at auction. There is no measurement for the sentimental value you might attach to the item.