In short, the grantor conveys property to the grantee through a deed. Either the grantor or grantee can require various modifications, restrictions, or covenants within that deed to spell out how the rights to the land can be further transferred, reclaimed, used.
1 The pyramids of Egypt are all built to the west of the Nile River. 2  This is because the western side was associated with the land of the dead. 3  The base of a pyramid was always a perfect square. 4  They were built mostly of limestone.
For instance, some claim that the pyramids were, as you mentioned, built by aliens. Some, however, claim that not only did the ancient egyptians build the pyramids, they also had batteries and even helicopters(!) as well. I doubt both of these theories very much.