Hortus Musicus, an Estonian musical group, was established in 1972 by Andres Mustonen, a violin student at the Tallinn State Conservatory. The ensemble specialized in performing early music, including European forms from the 8th to 15th centuries, such as Gregorian Chant and Organum, as well as non-European styles like Indian Ragas and Israeli temple songs. Hortus Musicus' repertoire also encompassed pieces by 20th-century composers, some of which were created specifically for them, including works by Arvo Pärt. The group's extensive discography includes albums such as Peeter Vähi: 2000 Years After the Birth of Christ (1995) and "Ave..." (2009). They have performed at major early music festivals and recorded approximately 35 programmes, with releases available from labels like Erdenklang and Finlandia Records. Notable members included Mustonen himself on violin and viola, Olev Ainomäe on shawm and recorder, and Ivo Sillamaa on harpsichord and organ.