We just purchased a home from the 1900 and in the upstairs hallway, this is in the middle of the floor!! What is or was this!!

HERE ARE SOME OF THE ANSWERS:

Button to summon a servant — We had one in the middle of our dining room when we purchased our house (built 1913). The people we purchased it from, who had had the house built, had live-in servants and that button summoned the maid to the dining room. The hostess could press it with her foot surreptitiously so that no one knew she was summoning the maid. The funny thing though is that when we actually moved into the house, the previous owners had removed the button — but left its fixture and wires. Our house also had two buttons in the pantry that rang bells on the 2nd and 3rd floors to get a servant’s attention and there was a speaking tube next to them so when the cook was in the pantry, she could talk to the maid or chauffeur who was on a different floor.
I know everyone is shitting on the idea of a servants bell but what else could it be from back in the day? Oh it’s in the hallway? Yeah, they stuck them everywhere in the old houses. Maybe this one just didn’t get complete torn out take a screwdriver and look inside
If it’s in the floor near a main door I suspect it’s part of a lock/door security. The lock on door would have a rod that connected to the floor, preventing people from kicking it in.
We had a servant button in the floor of an old home that my parents had fifty years ago. The home also had a coal chute.
Yep, butler call bell, our old family beach home had one under the dining room table!
You can see that’s a finger pole so whatever that is it was meant to be pulled out. It may have been quick access to plumbing underneath the floor. It’s been nailed in place you can see.