Here is an example of a 20 story office building in downtown Manchester, NH they just remodeled to 1-3 bedroom apartments.
This building had been a 20 story office tower since 1972.
Brady-Sullivan, who owns the building since 2006 is a real estate development company. They own multiple apartment complexes in NH & MA. Some are the mill type buildings I previously mentioned.
Here is an article about the conversion:
Manchester is a great city.
Unfortunately it is not representative of most medium and large cities in the country.
If you put that same building in Lawrence, MA or Camden, NJ or Baltimore, MD or Atlanta, GA or Chicago, IL etc etc etc it would be a slum in ten years.