If there’s no handy building big enough for your sign they can put it on one of these monsters, but if there is a handy building then job done. Though don’t forget that if it’s up that high it might look a tad smaller than the roadside jobs, and there’s a danger of crick neck when close to the building.
Many years ago I thought I’d arrived when one of my drawing appeared on a 64 sheet poster. That’s one of the uk posters that are at the roadside and not like this on a huge gantry. The state of “arrival” here I would think is when one has a poster on the entire side of a building, like the one below. 64 sheets is supposed to represent the number of separated printed sheets that make up a poster, so it’s pretty big. I doubt that they do it that way any more, certainly for the side of a building.