Although time and its measurement is a fundamental component of human life, a special type of clock which takes matters to the next level is the so-called astronomical clock and whose purpose is not to measure time per se but to convey astronomical information and, in particular, the relative position of the Sun and Moon as well as the zodiacal constellations and, in some cases, the position of the planets all as a function of time.

The oldest such effort to effectively emulate the overhead celestial sphere (ie a mini-planetarium) is the Antikythera Mechanism which was discovered in 1901 totally by accident by sponge divers off the coast of the Greek island of Antikythera. It has been dated to approximately 80 BC and it is believed to be the work of Poseidonius of Rhodes. The Antikythera Mechanism is currently on display at the National Archaeological Museum in Athens, Greece.

The gallery below involving astronomical clocks represents models which were first started during the Byzantine era thanks to intricate designs to document the dynamic nature of the Solar System's primary bodies as viewed from Earth, namely the Sun and Moon, with further efforts to depict the zodiacal constellations and the travels of the Sun and Earth across the ecliptic. These engineering marvels represent a European phenomenon and preoccupation with a particular concentration in Italy, Britain and France.

A more antiquated effort to document time using the heavens above was initiated by the ancient Greeks around 200 to 150 BC with the introduction of the asrtrolabe and which gained particular prominence about 800 AD and thereafter when it was widely adopted by the Islamic World in its efforts to precisely identify daily sunrise and sunset times due to religious obligations (vis a vis prayer times). The gallery below also includes astrolabes as well as their simpler counterparts (ie quadrants) with the samples from England, France and Italy having a dedicated (hyperlinked) page due to the shear volume of items available and which would otherwise overwhelm the country-specific collections below.