The week I had to rewire an entire 1920s house in Seattle because of knob and tube

The homeowner wanted to add central air, but the old system was a total fire hazard and we found live wires wrapped in newspaper insulation. It took four of us six full days to pull all new Romex through the plaster walls without wrecking the place. What's the most insane old wiring setup you've ever had to deal with?