The Latvian Song and Dance Festival (Latvian Vispārējie latviešu Dziesmu un Deju svētki) is one of the largest amateur choral events in the world and an important event in Latvian culture and social life. It is also a Masterpiece of the Oral and Intangible Heritage of Humanity. The All-Latvian Song and Dance Festival have been held since 1873, normally every five years.
During the festival’s exhibitions of photography, art and folk craft, orchestra concerts, and a festive parade also take place. Events and competitions leading up to the event occur throughout the period between festivals.
Approximately 30,000 performers altogether participate in the event. Although usually folksongs and classical choir songs are sung, with emphasis on a cappella singing, recently modern popular songs have been incorporated into the repertoire.
You can read more about this huge cultural event here.