Should I remark the water course or the historical construction (150+ years)?

Yes, interest rates are still at a historic low, almost 10 years after they trended down below the average for the past 100 years. 

I'd note that if capital appreciation is a goal for you, historically in NOVA lowered priced (and smaller properties) such as condos and townhouses will appreciate at a faster rate.

Historically during a government shut down, SEC 8 payments continued.  

You need to ask for a rent roll from the property and a full stack of historic expenses and see if the numbers make sense. 

You can tell from the price being discussed that it is a zero appreciation market (meaning historically it appreciated no faster than inflation). 

(It’s located in a historic area in the city)

I believe many/most of the RE investors starting today will not achieve a better return than the S&P 500 and are likely to exit RE investing in less than 10 years.Therefore, I am in the camp that most young investors would be better off investing in stocks, ideally using a ROTH, rather than enter a very competitive RE market that has shrunk cap rates in most markets that have any historical appreciation.

I'm a former real estate attorney who previously worked with investors on flips involving affordable housing and historic preservation tax credits, so I think I understand enough to be helpful.

I currently own a property in a historic district and was planning on selling the HTC's to pay for renovations.