Buy Land on the Moon
As far as unusable real estate goes, this isn’t a bad deal. Buy swampland in Florida and everyone thinks (actually, knows) you’re a poor, sad, gullible boob who’s open to being taken advantage of. Own some land on the moon, on the other hand, and you’re sort of a lazy pioneer. It’s a long way to go for a vacation, and whoever you give this to probably can’t afford to make the trip, but if they ever figure out how to make this whole space taxi thing work, their great grandkids might just get some use out of it.