Oldest extant magnetic compass,
from iron meteorite, pin on left side (now bent up) originally pointing North, the engraved figure demonstrates the variation of the length of days over the twelve month of the year (1st row June to January, 2nd row July to December). The object was used as a mobile sundial suspended on a string.

(1st century CE; from the Villa of the Papyri, Herculaneum, now Museo Archeologico di Napoli, Italy; catalog entry: "Object ID #335" in: http://www.ancient-astronomy.org/webapplications/gordon/SundialNavigatorProject/CurrentVersion/index.html)

[Alternative interpretation: bronze plaque to register the curing and aging of ham (bearing no relation to sundials).]