Charles Clay's Organ Clock, dated 1730, is the most important and ancient element of the collection of clocks in the Royal Palace of Naples.

The Palazzo Reale machine has a shrine-shaped case, in perforated silver, with a glass door, surmounted by an urn with eight pine cones on the sides. The dial bears the hours marked with Roman numerals, the minutes, every five, with Arabic numerals and the half hours with small stylized lilies. The two charging holes are also evident. The front face of the case is in copper painted in oil with the application of bas-reliefs and high-reliefs in silver that outline the scenography of a temple, at the top of which a concert of celestial musicians with moving limbs is depicted.

The clock is a pendulum clock, while inside the case the parts of the mechanical organ, made up of 51 pipes, are supported by a frame. Georg Friedrich Händel was a regular collaborator of Clay and he was responsible for the music programmed on the organ's cylinder. These are five adaptations of passages taken from works by Handel performed in London between 1727 and 1729 (Lothair, Siroe king of Persia and Richard the First king of England) and five pieces, not yet identified, probably composed especially for Clay.