hepf, thanks a lot for the photos, I always enjoy them
. And believe me, due to my work I know basalt very well... 
I studied photos from Orange, Basora, Sabratha... for me the most intriguing part is how the wall was covered (paints, marble...?), I havent't found too much information on the net.
Respect Cartagena, I have news.
The bad one (it depends of your point of view) is that I have too much work, so I can't work on it now.
The good one... this book:
I want to buy it, it has reconstructions of a lot of roman theatres, including the new hypothesis for Cartagena...
It's a big image, click on it:
http://i53.tinypic.com/oqzva9.jpg
Yes. Three floors, and fits perfectly with the fragments found.
So I am going to have a nice summer 