You might previously heard of a biennale. "...a critical site of experimentation in exhibition-making, offering artists, curators, and spectators a vital alternative to museums and other similar institutions whose institutional inertias do not allow them to respond with immediacy and flexibility to contemporary art's development." - Filipovic, van Hal, and Ovstebo 2010. A Triennale, lives and thrives by the same concept. However, it's instituted every three years.