Pictures?

Ill take some this morning

The more i look at it it does look like concrete or mortor with thick coats of paint

I had the same texture in my old house. The only way to remove it is to take down the wall and put up sheetrock.

What I did was use joint compound over it to make the walls have less texture and to fill in the cracks, etc. Basically I worked with the texture but made it less prevelant.

Replacing the undulations of historic plaster with the dead-flatness of modern sheetrock should only be a last resort.

Absolutely agree 1000%. Hoping the OP doesn't do it.

A slightly more cake frosting variation of this was done in a lot of houses where I grew up in the immediate post war era until the latter part of the 1950s, and depending upon the style of house, it appeared in some older houses, but around 1900 I would still expect wallpaper to be pretty prevalent, because papering was more DIY than painting prior to the introduction of the paint roller and pre mixed paint. That doesn't really answer your question except that it makes me think this may have been added on top of smoother plaster walls. Could be wrong.

But that part thats completely flaking off needs to be redone with new drywall right? even if it was added on top of smooth plaster how would you get everything off? I assume easiest would be to joint compound like cpartist said to tone down texture then do the other part to match. not a pro here though. i’m quite happy my 100 year old plaster walls are nearly as smooth as drywall.

I wouldnt twke the plaster off, its on a noisey street and it helps a lot with that as well as insulation the old stucco house is suprisingly efficient. i really like flat plaster walls with nice wood work but its a rental and that texture is not going to be pleasing to agerage people. well see ill hear theirbcomments. ill glue the loose pieces back and paint it light grey thank you everyone

I do believe it was done after the fact. the base and window trim are buried in it. about 1/4-3/8”

That doesn't really answer your question except that it makes me think this may have been added on top of smoother plaster walls. Could be wrong.

In this case you're wrong. My walls were almost exactly the same as the OP's in my 1898 house.