Way, way back in the day, in the second Castlevania game, I didn't know to use the diamond what's it at this one dead end to cross this unjumpable gap. To be fair, a lot of people didn't k ow that, either.

However, it turned out to only be mostly unjumpable; after (lots of) trial and error, I found that could *just barely* jump far enough to get a pixel of my character onto the ledge, and so jump across that unjumpable gap.