1. Baghdad Battery
Discovered in a Parthian village in North-Eastern Iran, the Baghdad battery dates back to between 250 BC and 226 AD.
It consists of a ceramic pot, a tube of copper, and a rod of iron, and experts believed that it was used as a modern-day battery.
It is believed that the charge produced by the battery was used to electroplate metals.
Electroplating (as seen in the image) was a process by which metals were covered with another metal (usually gold).
While this explanation on its own seems plausible enough, the strange thing is that batteries were first discovered only 2000 years later.