The Bell Tower was first built in the Ming-dynasty Yongle Emperor’s reign and then rebuilt in 1743 (the eighth year of the Qing-dynasty Qianlong Emperor’s reign) as a two-story double-eave building with a hip-and-gable roof. The massive bronze Bell of Supreme Harmony, known for its deep and resonant tone, hangs on the upper floor. It was struck when the emperor entered and exited the Fasting Palace.