Unique Fence Issue

[Scott J.]

I own a historical 1920s home that qualifies for the Mills Act, which reduces my property tax by about 40%. There are over hundreds of homes like this in my area.

Because this is an older home, there is some wacky zoning. One of our neighbors is a beautiful two-story Victorian home (maybe worth $700k) and our other neighbor is a six-unit apartment complex. 

There is a 8-ft. tall cinder block wall with vines between our home and the Victorian home. It's sturdy and offers plenty of privacy. Unfortunately, there is just a rickety 6-ft. tall wood fence between us and the apartment complex. Our home is also elevated a few feet, so there's no privacy between our home and the apartment complex. They can literally see us walk in/out of the bathroom unless we have the curtains drawn, but then there's no natural light in the living room.

We would like to build an 8-ft tall cinder block wall (similar to our one with the other neighbor) between us and the apartments. The owner of the apartments has agreed to split the cost too.

The issue is that the city is a nightmare to deal with because we have a historic home. My wife called the Mills Act people and they already said we can't build a fence unless it's wood and 6-ft. or less. 

It's possible the existing fence is on the apartments side of the property. I know their owner built it on his own. How can I find out? 

What would you do if you were me?

• Don't build the fence and risk losing the historic home property discount. (I think the risk of that is low because our other cinder block wall was just built, without checking with the city. The risk is there though, which makes my wife nervous!)
• Check to see if the fence is on the apartment's land and then build the cinder block wall. (If I do this, should we check with the city or just do it? Our city is notorious for always saying, "no".)
• Build the wall and bank on the city not noticing. 
• Any other options?