Intellectual property at least makes a certain sense, since it is something you create yourself out of thin air, and therefore can decide to make available to others under certain conditions if both parties agree. If you don't make it available, nobody suffers, and if you do, you have created value without depriving others, so it is only fair to receive compensation.
Owning land, on the other hand is clearly immoral. You didn't create the land, so how could you own it? Oh, you bought it from someone else. Well they didn't own it either. Someone stole it from the community a long time ago. Owning land is theft exactly because it is a limited resource.