The Federation Bells on the middle terrace, Birrarung Marr, Melbourne, commissioned in 2001, are a collection of inverted bells comprising nine different design types of various sizes from half a kilogram to 1.2 tonnes mounted on steel poles. The result is not unlike a collection of church bells, however they are spread through an open space rather than being confined to a tower, allowing people to walk between them. There are thirty-nine bells in total, spanning 3 octaves. Tuned in the just intonation system, the bells are controlled by computer, and play an ever increasing range of compositions, some commissioned, some submitted by the public. This sound sculpture plays three times a day. The bells were designed by Neil McLachlan and Anton Hassel. In 2010, Spring Innovations were asked to design a new dynamic playing system that was publicly launched on 1 April 2012. Since then the bells have played over 11 million times annually with near complete reliability.