The Astrarium: Giovanni Dondi and the Invention of Time
Ross King

In 1365, a brilliant Italian astronomer, clockmaker and physician named Giovanni Dondi embarked on a remarkable project: the construction of the Astrarium, one of the most astonishing machines of all time. Part mechanical clock, part planetarium, part medieval supercomputer, this masterpiece took sixteen years of meticulous craftsmanship to build. When finally completed, it did something extraordinary: it tracked the movements of the Sun, Moon and planets in real time with breathtaking precision, transforming abstract astronomy into a dynamic mechanical reality. Its nearly 300 intricately crafted components — gears, pinions and dials — worked in harmony to capture the rhythms of the Cosmos many centuries before computational astrophysics and high-precision astronomical observatories. It quickly became one of the wonders of the world, by far the most famous machine of the Middle Ages.

            The Astrarium brings to life the world of Dondi — known as the ‘prince of astronomers’ — as well as the city of Padua in all its cultural effervescence, with its radical ideas, artistic excellence and scientific discoveries. It explores how the Astrarium revolutionised timekeeping, bridged medieval and Renaissance thought, and laid the groundwork for the Scientific Revolution. Dondi’s clockwork planetarium became a formidable tool at a time when the ability to predict celestial events bestowed great powers on a ruler. In an age where knowledge of the heavens was closely tied to divine favour and political might, possessing such a device elevated the owner to a near-godlike status, making him an object of both awe and envy. Dondi’s creation was therefore more than an instrument: it was a statement of intellectual supremacy, setting both its maker and its owner apart in an era when science, philosophy and personal prestige were deeply intertwined.

            The Astrarium will weave together diverse sources to construct a vivid and multi-faceted portrait of Dondi — not only as a mathematical and mechanical genius but also as a deeply human figure, shaped by the intellectual and emotional currents of his time. Through his writings, correspondence and poetry, we will see Dondi not just as a master of engineering and astronomy but as a man of introspection, ambition and social connections, firmly rooted in the rich social and cultural milieu of the late 1300s. He became one of Italy’s first intellectual celebrities, a forerunner of the Renaissance, and a thinker driven by ambition, curiosity and the quest to master time, motion and the universe itself.