Which city would be good for a newbie like me to explore?

P.S. I'll be going up north this summer for a weekly vacation and they're along the way and I hear both are gold mines.

You are correct in saying they are gold mines, but I think Detroit is probably better. So many people go to Gary from Chicago. A lot of these people are Instagram people just looking for likes. I would recommend Detroit, spend some time doing research and find some nice places.

Depending on newbie level I'd say neither.

Posted by jeepdave Depending on newbie level I'd say neither.

I can't claim to be an expert on either, but I think Dave is right. That being said, there are safe and productive places in Detroit, but the issue is knowing where those safe places are. Detroit natives know which neighborhoods to avoid and which are just say, industrial areas, etc. (That makes it sound more black and white than it is, there's a lot of nuance) It's not necessarily "big scary thug zone" but it's also not a place to be taken lightly.. or so I'm told.

I'd assume Gary could be like that but on a smaller scale. There are a few good "first time" places in Gary that are pretty famous, do some research and maybe check those out.

Might be fun to meet up depending on where "up north" is, I'll shoot you a PM.

Gary... stick to the downtown/northern Broadway area for a while and you'll be fine.

Posted by jonrev Gary... stick to the downtown/northern Broadway area for a while and you'll be fine.

This.

My first time in Gary was around those areas, and I wandered the whole time with my camera round my neck on a beautiful sunny Sunday afternoon and felt absolutely fine.

Detroit I wouldn't go into without either people who've been there before or locals, there are too many variables in that city. My only trip there so far was with four others and we met up with a couple of natives along the way which was a godsend.

I have only been through Indiana in passing and never got to UE in that state but I've lived in Detroit my whole life. While there are still literally tens of thousands of abandoned houses, store fronts and smaller industrial structures, many personal favorites (my own and those of others) have either been torn down in recent years or secured.
For instance, the old Eastown and Madison theaters are gone. There was a great hospital and funeral home near each other that have since been sealed off and, last time I checked, the Packard Plant complex was being closely watched by security. I'm not sure about the current state of the Book Cadillac building but I know it was secured at least 10 years ago w/ some possible restoration going on.
Also, Mayor Duggan has stepped up the demolition program for some buildings in the area that have stood vacant for several decades. (Most of those are unsafe, fire damaged shells)
If you do decide to come to Detroit and have an interest in a particular building, I can cruise by it just to check the status quo.
Best of luck!