Our house is very old, and was originally built without running water, so the one bathroom it had was in an addition. In the years we have lived here, we have added another bathroom (extensive work, as the interior walls were not thick enough to hold modern plumbing pipes), gutted the kitchen down to lath, ripped out all carpeting and refinished all floors, moved a wall upstairs (all plaster, so it needs to be decided in advance whether to replaster or to use wallboard), replaced every window, resided and reinsulated. Oh, and we had a new roof put on and removed the unused chimney.
Ultimately, a very old home that needs major renovation is a LOT of work. I never would have done it except that this is the home that my DH grew up in and he was NOT going to tear it down and start over (with everything we've done, we really should have). Have any older home inspected before you buy and be sure of what you want to take on.
Small things can add up quickly. Asbestos was mentioned, for example, and a lot of older homes either have asbestos siding or asbestos flooring. Neither of these are dangerous provided they are not broken and the dust inhaled, but no professional will remove them without wearing full suits and ventilators. They need to bring in a special dumpster and you need to pay for hazardous material disposal. That means that just replacing the floor in a kitchen can run into the tens of thousands of dollars unless you do it yourself. And asbestos tiles can often be hidden under newer tile, so you can be in for surprises sometimes.
Anyway, old homes can be gorgeous and well worth the work. They just aren't worth it if you don't know EXACTLY what you are getting yourself into.
