Recent excavations at Segesta, sponsored by the German Archaeological Institute at Rome and published in 1984 by Dieter Mertens in the magnificent two-volume Der Tempel von Segesta (available for $2200 on Amazon!), have conclusively shown that there were indeed cuttings and trenches for the foundations of nave (cella) walls in the east and west ends of the temple. This is conclusive evidence that the Segesta temple was not meant as a hybrid open air structure for local Elymian cult. It was meant to look like an honest to goodness Doric style Greek temple; the thing is that it was only half-finished.