Russia issued this stamp (Scott 4150) in 1973 as part of a set. The stamp features the exterior of the Riga Dom (cathedral) and includes a representation of the organ. After having served as a concert hall in the Soviet era, the Dom is now once again a worshiping community. The organ was originally built by the EF Walcker firm in 1883/1884. It was most recently refurbished by the Flentrop firm between 1981 and 1984. As it turns out, I visited the Flentrop workshop in Fall 1981 and saw some of the work being done on the Riga Dom instrument. The organ, according to the Dom website, has more than 6000 pipes, from 10 meters in length to a mere 13 millimeters! One can see a nice history of the instrument here, and see the stop list here.
