Giovanni Dondi dell'Orologio, also known as Giovanni de' Dondi, was an Italian physician, astronomer and mechanical engineer in Padua, now in Italy. He is remembered today as a pioneer in the art of clock design and construction. The Astrarium, which he designed and built over a period of 16 years, was a highly complex astronomical clock and planetarium, constructed only 60 or so years after the very first mechanical clocks had been built in Europe, and demonstrated an ambitious attempt to describe and model the planetary system with mathematical precision and technological sophistication.