The Altar to the Unknown God from Palatine Hill in Rome: 

The inscription itself does not contain the words “to an unknown god,” but nonetheless, the museum’s identifier attached at its base reads as follows: “altar of the ‘unknown god.’” It likewise contains the following inscription: “Whether sacred to a god or goddess, Gaius Sextius Calvinus, son of Gaius, praetor, restored this on a vote of the senate.” In other words, Gaius didn’t know the god who was once worshipped at the site of the altar he reconstructed, nor did he know if it was a god or a goddess.

The 'Water Clock' from the museum in the Athens stoa: 

his water clock was used to time speeches in antiquity. Water would be poured into the top bowl and escape into the lower bowl through the narrow spout. It was said that the most practiced orators could finish their speech just as the last drop fell into the pan.