Stairs and inclines, like steep hills and tiered seating. We can’t sit in the cheap seats at sporting events because I constantly feel like I’m going to fall and I get anxiety attacks. Stairs and escalators are bad too, but I’ve gotten much better with those over the years (can’t exactly avoid them in most cases).
I have a 2 story house with a basement, and even going downstairs in my own home can sometimes be hard.