So the first house we bought was 90 years old. Loved our little red house. It was right across the street from the hospital, which as a resident was great. After not sleeping for 30+ hours, I could just stumble across the street. And when the Munchkin was in the Neonatal ICU, I could tell they had put her under phototherapy because the blue glow was visible from our house.
But the house had its quirks just like any old house does. The house had 1 full bath, 1 half bath, and 1 added on 3/4 bath in the master. And each of the bathrooms weren't quite right.
I will start my plumbing stories with the first bathroom. It was the half bath on the main floor. First off, the door opened into the bathroom - but instead of going towards the wall, it hit the toilet. So you couldn't actually open the door all the way. You would have to walk in, then creep by the sink, and then you could close the door. And the sink wasn't against the wall - but maybe 6 inches away.
So I had the grand idea of making everything work. Ripped out the sink, door, and lights. Moved the sink over 6 inches. Had to redo the plumbing to fit that distance. Used some flexible hosing, and they even make a little rigid drain pipe that has a segment of accordian pipe so that you can bend it a bit and make it fit.
Tried to move the lights. No good. Plaster wall with gympsum board behind it. Don't ask. Have no idea why it was made that way. Chewed up all our drill bits (um - if you should ever encounter this - use masonry bits. General drill bits don't work. But I tried anyways. And now we need a whole new drill bit set.) Finally had to hire an electrician to move the lights and the wall switch (again it was behind the door).
And after that we had a fully functional bathroom that you could open the door and walk in at the same time. A marvel of modern home building. (No pictures of this project. But I do have some of the other bathrooms.)