When she learned to crawl, we had to put up our first barricade at the top of the stairs that lead to the basement. We couldn't put up a baby gate because the cats' litter box is downstairs. So we improvised.
We also liked to be able to work upstairs without locking Miss F in one room. So we bought an extra tall wooden baby gate, but found that it didn't fit with our chair rail. We'd have to cut pieces of the chair rail out. So we bought a plastic one instead:
It was a big pain trying to move this heavy, cumbersome chair when I had to get upstairs. And I have to go upstairs fairly regularly. So I pulled that gate out to see if it would stretch. It didn't, but I managed to make this instead: