It was pretty boring. I mean, it was like any other slightly shabby northeast town. It was billed as having a strong artisan/artist community drawn by the lower housing costs, but they'd actually mostly drifted away to the cities years earlier.
Negligent absent landowners would have to be taxed A LOT to get them to maintain and develop property. Obviously they don't mind making nothing on the property for years anyway.
Better would be confiscating neglected land after just a year or two of neglect... Give it to someone who will use it. (For owners who do care, but can't afford to do the repairs, well, it would be cheaper to help them out probably.)
I don't live in Detroit or Delaware, but in a city neighborhood-- a nice working class neighborhood, mostly "Levittown" style small frame homes. There's one house down the street that was partly burned by arson 11years ago, and has been boarded up and abandoned by the absentee owner. But the city just slaps more penalties on year after year, never condemning it, though the lot could be sold to a family for building.
So I see the problem, but I think that mere taxing land wouldn't solve the "too rich to care" owner problem. (Or the "too poor to fix" one either.)