The bells that still play

曾侯乙编钟 · zēng hóu yǐ biān zhōng

Sixty-five bronze bells cast in 433 BC, each producing two exact notes, spanning five octaves. They were played for the world at the 1997 Hong Kong handover and remain in tune today.

Found in 1978 when soldiers levelling a hill in Suizhou hit a flooded tomb. Inside, beside the bells, lay the Marquis Yi of Zeng, 21 young women, and 15,000 objects — the richest Warring States burial ever found.

Each bell has an inscription in gold explaining which note it plays in the scales of five different states — a 2,400-year-old music theory textbook. The set proves China had a complete chromatic scale two centuries before Pythagorean tuning spread in Europe.

The originals are never struck. A perfect replica is played at the museum's bell concert several times a day, together with Chu dance and the 25-string se zither.