It consists of enormous 6718 pipes.
Ferenz List, one of the most outstanding musicians of the 19th century, composed a special piece upon the opening, dedicated to the organ, Nun danket alle Gott.
For visitors of Riga it is great news since organ plays concerts every week. So when you are in Riga this is a must do.
Here you can read more in detail about the organ and a list of concerts.