I received a letter one time when they were doing heavy construction near by.

It looked like the city was trying to inspect my house and I later found out it was a contractor for the construction company wanted to cover his butt before he started blasting.

Make sure it is legitimately the city.
If it is, then see if you have the right to decide to let them in or not. (Don't take the cities word for it though)
Then decide if it is worth letting them in or not if you have a choice.

I had a inspector come by one day. He quoted my square footage and asked if I had remodeled the basement to living space or not. I said no, inspection over, he never left the sidewalk.

They tax on livable square footage here and that was all he needed to know.

Best of luck.