When building the Jefferson Memorial, how did they lower the huge dome into place without cracking it?

Question

What did they use to accomplish that?, and not talking about cranes

Answer 1

It isn't a single piece brought to the site. The dome has a concrete core with the limestone facade mortared over it.

Answer 2

if it wasn't cast in place, I would say they filled the thing with sand, then let the sand trickle out lowering the dome onto it's supports. thats how it would have been done in ancient times.

edit;

Ok, I'm close ,was it water instead of sand?