Baghdad Battery

The Baghdad Battery, also known as the Parthian Battery, is the common name of Mesopotamian artifacts discovered in 1936 near Baghdad (hence the name.) They were probably created in the Parthian or Sassanid period, between 250 BCE and 640 CE. In 1940, Wilhelm König published a paper speculating that they may have been galvanic cells, batteries, perhaps used for electroplating gold onto silver objects. This interpretation continues to be considered as at least a hypothetical possibility. If correct, the artifacts would predate Alessandro Volta's 1800 invention of the electrochemical cell by more than a millennium!

The pots contain an electrochemical couple of copper and iron, and so if one were to place a suitable acid, such as lemon juice, grape juice or vinegar, an electrical current would form. The voltage, however, would be very low with this particular pair of metals.

Antikythera Mechanism

The Antikythera Mechanism is an ancient mechanical computer built by the Greeks to calculate positions of astronomical objects. It is the world's oldest known analog computer. Recovered in the beginning of the 20th century from the Antikythera wreck, its significance was not completely understood until decades later. It is phenomenally accurate in its calculations of the positions of the moon and planets. Estimated to have been built sometime between 100 and 150 BCE, the technology was lost with the Ancient Greeks.

Similar works didn't start to reappear until the 14th century, which makes the Antikythera mechanism outdate them by over thirteen centuries!
The complexity of the device itself is more similar to the creations of 19th century Europe.

The device is displayed at the National Archaeological Museum of Athens and even has a project researching it, aptly named The Antikythera Mechanism Research Project.