Building Greek fire devices

The medieval Siege Workshop tells me that at L.10 it can produce Ballistas and Catapults. It doesn't mention Greek Fire.

Is that from the same building at a yet higher level? Or what?

Greek Fire is trained in the classical age siege workshop. Not in the medieval workshop. It can be trained at level 5. 

However if you researched ballista, then you can not also research Greek Fire.

Thank you, Mari!

I did mean Classical (not Medieval), as opposed to Primitive. And I'd made the mistake of trying to figure out what was ahead for one hero by looking at another whom I'd sent on a different Research route.

Now I know I just need to upgrade to L.10.

Old George sometimes when I have questions about what certain buildings will allow me to do, where something is upgraded, what it is for, I return to the research tab. There is actually quite a bit of information there. In the case of the ballista/greek fire choice, I thought it is really well  defined.