I don't seem to be able to build towers in the WBC3 campaign. Is this because I chose a Knight, or are towers disabled in the campaign? Thanks.

In the first mission, or any? There are some missions where Towers are disabled (It's a map setting). However I'm sure I built them in some missions. I'll fire it up now and have a look.

Just tried it, Towers build fine for me when playing as knights in the second mission (Recapture the rift). How are you prevented from building them, are they not there, or simply greyed out? If the latter, do you have enough resources?

They are simply not there. Is there another tab or screen besides the main building screen?

I've managed to get by without them, it's just annoying.

Yes, there are 2 separate building screens. You can only build core structures with your hero, but with a peasant you have a separate set of options next to the main building icon.

Thank you, I knew I was missing something. I haven't played the series since WBC1 & 2 were new releases in stores, so I could not remember what the trick was.