Cairo is an interesting place. It is pretty small but its role in the Civil War was quite large as it served as a staging area for riverine operations in the West. Early in the war it served as Grant's headquarters and his desk is still there. Even Grant's desk shows that he was always ready for movement as there are little plastic wheels on the bottom (yes I know those are modern additions but its a tiny joke).
I went to Cairo though on a Shiloh hunt. I had read in a book that the Tigress's flagpole was in Cairo. This was the ship that Grant used to get from his headquarters at the Cherry Mansion to Pittsburg Landing for the big battle on April 6th. My book said it was downtown somewhere, I think near city hall. So I went there but instead found this cannon.
I was discouraged but kept driving around. After no luck I finally stopped in at the Chamber of Commerce. Where I learned that the locals do not pronounce the C in Cairo. I knew it wasn't pronounced like the city in Egypt but I was surprised that it sounds more like a-row. In any respect the lady there called the librarian to ask, which led them to a museum and that's where they suggested I go. Which brings up a wonderful tip. You can buy all the guidebooks in the world, do tons of preliminary research but if you ignore talking to the locals you can miss some gems. I went back to the museum and there I found the flagpole, which to me was a true gem. The flag is obviously a modern made version but the flagpole, and original wooden historical marker, are fantastic. I had the museum to myself that day and wonder how many people have ever seen this treasure. I'd wager that more people will see it here today than will see it in person today.
The desk and the flagpole are in the Cairo Custom House Museum.