Hi Edita,
I just got back from looking at a 133-year-old house. They definitely come with their own set of problems. You also need to keep in mind your exit strategy - an old house flip in a gentrifying neighborhood can be wonderful, but an old house with deferred maintenance in a middling neighborhood...well, not so much.
The things to look into are the same with any purchase. You just have much higher odds of having more expensive things to correct - knob and tube wiring, asbestos, no insulation of any kind, etc. Also, lead paint will add an additional margin to work being done.
On the plus side, you'll often find woodwork, stained glass, and other ornamental work that's quite valuable. Structural members are often true dimensional (the house I was looking at had massive joists.)
If you're doing it from afar, you really need to get someone on the ground who has experience with old houses. I've run into a fair share of inspectors who, while well-intentioned, don't understand the issues with older houses.
I'd also suggest building in a higher slop amount, as there's frequently hidden damage or other lurking problems.
Good luck!