Astrolavos is the first device that looks like the analog calculators we use these days. One of these devices was found  from divers in the bed of AntiKithira (among other archeologic glealings) in the Aegean Sea, near Krete in Greece. These days you can find Astrolavos in the Museum of Athens.

Astrolavos was used in observing the stars and calculating the height above the horizon (around 200 B.C.!). The "Astrolavos of Antikythira" is an extremely compicated device and it's function isn't determined yet. The first who ever made such a device was Ipparxos, a great astronomer of Ancient Greece.