It seems to be this is born from some indecision regarding Rome's UA, since Gazebo said the NW is basically an extension of the UA that just comes later and needs to be built. It sure is powerful but wouldn't it be better to scrap the NW, merge its effects with the UA (lose some in the process) and get a useful building instead?
You could remove the "No buildings are destroyed when Rome takes control of a City." effect as it's directly going against the "+15% Production in all Cities for Buildings already present in Capital.". At least, it feels a bit schizophrenic to have both on the same civilization.
The UB could be some amphitheater replacement that uses the "When you conquer a foreign City, the City immediately claims additional owned and unowned territory." part, when built in foreign cities.
UA could then be: "Whenever you win a battle, gain production and culture in Rome and the nearest city. City connections grant additional happiness and gold. +15% production in all cities for building already present in the capital."
I feel that would have a nice balance between infrastructure and military.