In the eighteenth century, the Sansevero Chapel was connected to the Prince’s palace by an overhead passage, containing a little booth housing a great clock with chimes. This wasn’t the only one to be designed by di Sangro. Another clock, perhaps even more spectacular and baroque, was to have been used to embellish the palace courtyard, but there is no evidence that it was ever finished.

The first record of sophisticated machinery comes from the eighteenth-century Short note on what can be seen in the house of the Prince of Sansevero. In a location near the bridge between the di Sangro home and the mausoleum was the “clock device” which, operated by a musician, played “any air” you could wish for on the chimes. The music was played on the bells, placed within a round temple with eight columns, and was audible some miles away. The “chimes” of the Prince of Sansevero were at that time the only ones of their kind in Italy.

Di Sangro himself described the second clock. As well as marking the days of the month and the week, hours and minutes, it showed “the different phases of the moon”, which at night appeared “luminous and clear, wholly true to the real one”, whether it be full, waxing or waning. At midday, allegorical figures would come out of four openings, which, moving in dance step with musical instruments in their mouths, performed “a finely executed march”. In the place of the pendulum, there was the head of a dragon, whose claws rang the hours and the quarters, striking the bells.