*Chris* - Well let’s assume your skyscraper is standing in isolation, so it’s not going to get your view blocked by an adjacent building for instance, so there’s no get out clauses like that. It’s a building in isolation in the middle of nowhere.

There’s a sort of approximation for distance to the horizon in miles which is 1.23 times the square root of the height of your eyes above the ground in feet.

So you could work out, using that little rule, how much further you're going to see if you go up the height, in feet, of one storey in a building, and then you could keep doing that to work out how much further you're going to be able to see to the horizon from the top of the building than the bottom, for example.