Here is a link to a post on the Alien Explorations blog that makes several interesting observations about the Hall of Heads inside the PFH temple, primarily from a production standpoint.
The blogpost links to several interesting articles; below, I quote excerpts from two of them that I think add useful information to the PFH puzzle:
About the stairs in the Hall of Heads: “The stairs were built for creatures with much longer legs than humans. Each step requires concerted effort – you don’t walk up the steps as much as you literally climb them. It may be a movie set, but it’s huge. This place wasn’t built for us. We don’t belong here.”
I don’t think in and of itself is sufficient evidence to posit that the PFHs are, in fact, engineers; rather I think it suggests that the temple, or at least more specifically this Hall, were built by the PFHs *for* the engineers.
About the Heads themselves: “we paid a visit to a particularly stunning set called “The Hall of Heads,” a monumental section of the temple where the walls are lined with sculptures of giant, you guessed it, heads. And I do mean giant. The heads were easily taller than anyone standing in the room, each one a distinctly carved face glowering into the center of the sacred room. It’s evocative of the pyramids we saw on LV-223 in Prometheus but different, more weathered and less industrial. Where the pyramids were angular and slick, the Hall of heads is a rounded, earthy room. Scott told us the faces might be those of apostles, wise men — a superior people, while production designer Chris Seagers revealed that the heads were meant to give a sense of history and gravity to the sacred place… a place where the Engineers stored their information.”