Rare '20s maps of lower E Side

[xdet]

The two pillars in the lower right hand section of the photo you posted were guide posts for freighters. There was also a seaplane hanger at Windmill Pointe back in the very early 1900s thru the teens. Nice Video of Garwood. If I remember correctly I think the maps came from the sanborn site.

My grandfather worked on those seaplanes [[the first built in Detroit), here are two photos from that era-

And a second one with grandma's notes on it, I never did find out who the brothers were that she mentioned on top of that first photo.