The original picture from the listing
What we found after we took the old flooring up. We knew the two floors weren't level. When you walked over the crack, you could feel the flooring spring down over the crack. 
The original terrazzo floor is on the left. The additional concrete floor was installed over the original lanai floor, which may or may not have been removed. It looks like the the addition has lifted about 1/8" but the original floor is load bearing so maybe it sank.
Now that the entire crack is exposed and having put a level to both floors, the concrete pad that was poured over the old lanai floor has lifted. The terrazzo floor is dead flat. The concrete has to be ground down to meet the terrazzo or chipped away and filled flush with the terrazzo. 
With the room stripped out, we can begin the remodeling. 
This took me about 10 minutes to chip away. It came off the terrazzo pretty easily. 
In order to achieve a levelness (I made that word up) that is undectable to the feet or by a visual looking from a distance, I have to taper the chip out about a foot into the concrete. If I didn't do that, the floor leveler would have to float out onto the terrazzo over three feet. 
Finally done! I think my bones were chipped too. 
The bubble in the level is almost dead on. The floor leveler will finish the rest. 
Grinding down the high sport - Tent setup to contain the dust
Without the plastic tent - (2) 20" box fans each with a 1" pre-filter and a 5" MERV 12 filter pull in the dust during grinding. The vacuum attachment could not keep up with the amount of dust created.
