Ancient technology was ahead of its time.

 Ancient technology was ahead of its time. 

"Image from an illuminated manuscript, the Madrid Skylitzes, showing Greek fire in use against the fleet of the rebel Thomas the Slav." (Wikipedia/Greek Fire)

We all heard things like Antikythera mechanisms and Greek Fire that could be a saltpetre-alcohol mixture. That thing causes extremely high temperatures. But it's possible. That ancient wise people knew things about centrifugal guns. Things like Aeolopile and Archimedes' Screw could use to shoot ammunition against the enemy.

"Animation showing how the Archimedes screw works, with the red balls representing water." (Wikipedia/Archimedes' screw)

 It's possible. Some ancient people knew that if they sent soundwaves to iron nails that thing sends resonance to enemy iron equipment and breaks those things. If that resonance will send through the sea. Enemy ships will be put together using iron nails that resonance can break the wooden structures around the nails. Those things are hypothetical ancient wisdom. 

"Drawing of the Baghdad battery's three pieces"

Also, things like hot air balloons and flight could known in the ancient world. In some theories, some ancient civilizations could know that if lightning hits spears or arrows those things would get strange forces. So those ancient wise men used natural electricity for making electric weapons. 

Even if famous Baghdad batteries are fake the ancient people must know that the metal bite is on a wooden platform. And if lightning hits it, that thing loads electricity to the metal bite. And things like electric fish can be used for loading those metal bites or capacitors. So the ancient people knew electricity. And they must know the places where they could load their electric equipment. 

Could Stonehenge be part of an ancient communication network?

In some visions, Stonehenge could be some kind of ion or plasmoid system. If there are mirrors that aim sunlight at the middle of the stone ring, that thing ionizes that gas. And then the druids could use things like magnesite bites to aim the plasma into wanted directions. That thing is one of the most exciting theories of the Stonehenge. 

The stone rings are in the middle of the network of stones. That thing makes it possible that the ancient stone rings are part of an ancient communication network where resonating stones transmit information. 

https://bigthink.com/the-past/examples-ancient-technology/

https://en.wikipedia.org/wiki/Aeolipile

https://en.wikipedia.org/wiki/Archimedes%27_screw

https://en.wikipedia.org/wiki/Baghdad_Battery

https://en.wikipedia.org/wiki/Greek_fire