Imperial Bösendorfer

For 90 years it was the only concert grand piano in the world with 97 keys,[3] until it was joined in 1990 by the instruments of Stuart & Sons of Australia.

[1][3][4] Bösendorfer built the first Imperial in 1909, following a suggestion by composer Ferruccio Busoni to build a model with an extended range.

While the keys are seldom used, the extra bass strings create additional harmonic resonance that contributes to an overall richer sound.

[1] Bösendorfer Imperial Concert Grand pianos, handcrafted in Austria, retail for between US$256,000 and $560,000 in the U.S., depending on finish, design and whether the Disklavier Enspire computer reproducing system is installed.

[7] (Bösendorfer's CEUS reproducing system, "Create Emotions with Unique Sound", developed in-house, is more expensive still.)