Is this building only limited to the city settlement of the province you start the campaign in? The building shows up in the building browser of every other city settlement you own, and if you try to build it in one of these other settlements it says you don't have enough space, even if it isn't presently built in your starting province's city. So either it should be listed as a unique building on the province when playing Achilles and shouldn't show up in the other provinces building browsers, or if it is supposed to be limited to one per faction it should list that, or there is a bug preventing it from being built in other provinces.
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