Yeah, cities can be Razed, but that function requires some research. I'm not sure which research actually produces it, but I'm guessing it is in the Civics line.

you have to reasearch fortress, this I think is super stupid that an army doesnt know how to raze a city,

but if you capture and empire city you can build your improvements on top of there dbling the cities production. this has to be an exploit through

just want to add fortress is a late game tech as well

Is it fortress for the empire side? Cause it's fortifications for the kingdom side.