This one shows a medieval castle type structure built on top of the original structure, to the upper left, with poorer quality, smaller stones. Notice how the top stones with the gaps between them are missing in the shot from the south-west. Once again, look at the terrain compared to that first picture.
I could write a book on this series of pictures. Notice the wall coming across from the third pillar, coming toward us to the right, made of somewhat smaller stones. That is the wall in the background, but not very far back, from the easterly view from inside the temple. Then look at the picture titled
Façade of the Temple of Jupiter, Baalbek
and that wall is not there. One can compare the stones along the top of the pillars as they go to the right, just visible above the wall in the above shot but clearly visible in the facade shot. As old as it looks, that wall had to have been added after the facade shot but before the shot with the wedge stone fallen to its position in the easterly view from inside. Note that in the facade picture the wedge stone is still in place, which makes it prior to the picture above and the one with the wedge stone fallen, the easterly view.
To summarize my somewhat rambling comments on this very interesting series of pictures (I was commenting as I went); it appears someone was trying to turn the Temple of Jupiter into a small fort. They built that wall across the front, blocking the huge doorway, and they built that watch tower on top of the pillars on the left. Apparently they didn't have any reverence for Jupiter.
Here are a couple more pictures that relate to this series, from the Library of Congress. We can tell that these two pics are later than the ones in this series because the extra wall that has been built across the facade, above, has been torn down, though the fortification on top of the pillars is still there. Temple of Jupiter, interior, Baalbek, Holy Land, (i.e., Ba'labakk, Lebanon)] digital file from original
