Smiths

[Morty]

My question is, what determines what the max smith level of a city/castle?

I thought it was dependent on whether or not there was a mineral in the province, i.e. iron or tin? This cannot be however, because in my Byzantine game Nicaea can upgrade to maximum smith building yet it has no ore in the province. Ok, so I figured maybe if they are "trading" the ore with a nearby province they can build a max smith. They are currently only trading glass with Constantinople. Hmmm maybe only "metropolis" can achieve this? That also cannot be the case, Corinth has a silver mine and is trading iron with someone and can make a max smith building. Next door in Athens they are also trading iron but can only make the first three levels of the smith. In my English campaign Caen can only make a leather tanner...

Please explain this for me, or point me in the direction of where I need to go to read up on this.

Morty

[Taiji]

Iron or metropolis are required but then only metropolis' will be able to build the huge walls or citadel to accomodate it.

[Morty]

I did some research into the export building desc file and found this out, which I'll share for those who had the same question as me.

Metropolis or iron (only) in a province = max smith level is attainable

If not then

Cities can attain up to a level 3 smith (out of 6)
Castles can attain up to a level 1 smith (out of 6)

Morty