At some places the concrete was poured in behind the wall between it and the shelving cliff, at other places it is built up like the wall. The marks of the stones in the concrete can be seen most plainly near Porta S. Martino (Fernique, Étude sur Préneste, p. 104, also mentions it). The same thing is true at various places all along the wall.
Fernique, Étude sur Préneste, p. 107, has exact measurements of the walls.
Fernique, Étude sur Préneste, p. 108, from Cecconi, Storia di Palestrina, p. 43, considers as a possibility a road from each side, but he is trying only to make an approach to the temple with corresponding parts, and besides he advances no proofs.