I am not one to pore cold water on a good idea but from the start there are some verey clear differences between what they had in those days and today.
For a start, electric drills were not easy to get at that time.
The wood would have been ceader not deal.
Secondly the artist of the day were pretty good and sad to say their boats looked a whole lot different than the on built.
Even using back hoes and bulldozzers it would have taken twenty years to build the waterways spoken of plus the building, all of which would have to be there to start with.
Taking into account the whole structure is supposted to have been guilt in twenty years
Time is most definatly not on their side.
In the video only limestone was cut, taking into account that granite was the most used stone, firstly is a lot more weighty that lime stone and secondly is a dam sight harder.
All that can be said for certain is somebody built these, but the lenght of time and the methods are still not known, even getting one of those blocks of lime stone still leaves a question how did it get to the top of the structure?