The circus was hugely popular in the Soviet Union. As Wikipedia notes in their history of the Moscow State Circus, "Officials considered the circus to be culturally on par with the Ballets Russes or Tchaikovsky, but was much more affordable, and therefore more proletarian, at only about five dollars per ticket. The Soyuzgoscirk established seventy circus buildings across the USSR, and entire towns would turn out to see the shows."
You can pay a visit to one of these buildings -- sadly now abandoned -- in Moldova and learn about its history and more about the history of the Soviet Circus in "Sneaking into an Abandoned Soviet Circus in Moldova".
(Click on image to enlarge)