I also had the documentation in case there was issues with the future buyer.I use a product called Serum which is hydrogen peroxide based.

That's caused by badly sealed or single pain glass & you not wiping it up when that happens.Better to use hydrogen peroxide rather than bleach when cleaning mould.

I've moved recently and can't lay my hands on the product I have left.One of my friends says this formula works but I've never tried it: 5 oz hydrogen peroxide1 tsp vinegar1 tsp baking soda1/2 tsp dishwasher orange soap (something about the orange scent help break up the urine smell), or for best results use 3 drops of wild orange essential oilMost of us won't rent to tenants with cats for this reason....it's hard to get out AND every other animal that wanders by going forward....will mark the same spot.

Clean it with hydrogen peroxide and paint over it with an oil based primer paint.

Just a note about the hydrogen peroxide, an oxygen bleach.  

One can also argue that our actual existence is also limited to the Table of Elements and we are mostly water, Hydrogen and Oxygen.

Intel is a great example, who is building the largest chip manufacturing plant in the US right here, and it will be a $20 billion dollar investment that brings a few new thousand jobs.https://www.dispatch.com/story/business/2022/01/21/intel-ohio-building-computer-chip-factories-licking-county-jersey-township/9173472002/ Another example of economic growth is the upcoming Ohio State University Wexner Medical Center Inpatient Hospital which is a 1.9million square foot hospital that will bring over 800 new beds and a thousand new jobs. https://abc6onyourside.com/news/local/new-osu-hospital-expected-to-transform-health-careHere are a few more recent investments https://www.10tv.com/article/money/business/hydrogen-power-company-hyperion-bringing-700-jobs-to-columbus/530-25907aab-5517-4661-a9f3-d2ed2d5be6b0 https://news.wosu.org/news/2022-02-08/rumpke-to-build-50-million-recycling-facility-in-columbus Check out The Complete Guide to the Columbus, Ohio Real Estate Market which goes through the Columbus, Ohio market in depth and will give you a better scope of where the highest levels of growth are taking place and where to look to invest.  

I scraped off crystallized dried cat urine from the floor in double garage, using a garden hoe, then we power washed it, used hydrogen peroxide in gallon jugs from beauty supply applied that to help get more of the urine up and off..

https://www.10tv.com/article/money/business/hydrogen-power-company-hyperion-bringing-700-jobs-to-columbus/530-25907aab-5517-4661-a9f3-d2ed2d5be6b0 https://news.wosu.org/news/2022-02-08/rumpke-to-build-50-million-recycling-facility-in-columbushttps://www.restaurantbusiness...

You can't really tell about the plumbing behind the walls, if you smell sewer gas ( hydrogen sulfide), it may mean a broken pipe or empty p-trap at sink or tub.