Is this how they did it?

In the past I did this to ants for fun.

Had a glass panel, the size of a football field to Kut 20 to 40 ton blocks of granite

Fair speculation! With so many tools to use in present day, always a risk of over-engineering. Reminds me of the "space pen" story where the Americans researched a special zero-gravity pen while the Russians just used a pencil.* *sometimes over-engineering is necessary ;)

The real question is how did they move the 1000+ Tonne stones ?

Wow

How else would the narrative fit so snugly? It's like putting on a well-tailored suit. Just remember, appearances can be deceiving. Dig deeper, and you may find a whole wardrobe of startling revelations.

It's a Fresnel lens,

I doubt they could produce Fresnel lens.