Dodona

Dodona is the site of the oldest oracle in Greece, probably dating back to at least the 2nd millennium BCE. It is thought that a settlement may have existed here as far back as 3,000 BCE, possibly making the oracular site even older.
It is said the priests and priestesses served at a sacred oak* at this site, interpreting sounds in the trees as messages from the Mother Goddess, likely Gaia, up until about the 5th century BCE when Zeus worship began with Zeus taking residence among the roots of the sacred oak. The Mother Goddess was renamed Dione and became the consort of Zeus.
Buildings didn't begin to appear until the end of the 5th century BCE. The pictures are all taken if the ruins at the large and extensive site.
The 1st picture is of the single largest structure, the amphitheater. There is currently some restoration work in progress. The 2nd picture looks at the old Christian basilica, dating to the 5th or 6th century CE. The 3rd picture looks from the basilica back over ruins of older temples toward the civic buildings at the site as this was an administrative center as well as a religious site. The 4th picture is of civic buildings.
The 5th picture is looking at the teme if Zeus with an oak tree within it's walls. It is said that the original temple was built around the ancient sacred oak. The 6th picture is the temple if Heracles. Part of the basilica was built over this temple.

*The notion that a sacred oak was the center of their religion has me wondering if there might be some ancient connection to the druids with their sacred oak groves.Read more