I didn’t really stand around and listen to the guides talk to their groups, but I did overhear one guy (in authoritative British English) say that this is the oldest temple here, and another say the white marble came from Ephesus (west coast of what is now Turkey). Both mentioned that the white pillar to the left of the steps supports a sundial. One of these three tidbits is mentioned in the WikiPee entry for this, the Temple of Apollo at Pompeii.
I might have given you a photo of a (wild?) poppy or a hedge (huge, mind you) of rosemary, but here you go with the imposing columns thing.
I found the sundial and a large water basin to the right out of the frame particularly interesting. They indicate this wasn’t a pure Greek version of Apollo-worship being replicated, but a Romanized approach to the adopted Greek deity.
That lump in the far left background is the monster that did in Pompeii in AD 79. P is on a hill relative to the sea (Gulf of Naples) and the Sarno River to the south, although it doesn’t look like it on Google Maps. My sense was this temple was on the highest point nearest the water, although there’s architecture between it and the edge of the Pompeii landform. Anyway, plenty to ponder here.
This must have been spiff-up day for the park personnel, as the grass was newly cut (not mowed).