I normally would have given this word a miss, but the DD etymology got me so riled, I had to address it.
Pantheon derives from the Greek (finally! not another Latin origin) "pan" for "all" and "theos" for "god", so pantheon literally means "all the gods". There is nothing about a structure, despite what DD says. The Greek system of worshiping the gods was not restricted to a single building, but was a way of life which was embodied in all activities, much like many modern day religions which are not merely restricted to Sunday or Saturday services. To speak of the Pantheon then with a capital P was not referring to a temple, but to the Twelve Olympian, which represented the important gods, and the other gods were facets under these twelve (See e.g., Hermes, Hermes Argeiphontes, Hermes Cthonious (overlapping with Charon), Hermes Cyllenius, Hermes Trimegistis, Hermes Psychopompos (overlapping with Somnus, and his son Morpheus)). Gods not associated directly or indirectly with the Olympians were prior ancient deities being phased out as having been defeated by the Olympians (Titans and their "monstrous" progeny), deities in contravention to the Olympians for point of conflict (literally, Eris), and the vague deities of nature (e.g., Gaia, Eos, Nyx). So, to speak of the Pantheon is to speak of the twelve greatest gods of ancient Greece, and possibly the twelve greatest Roman gods as the same were subverted entirely into their religion. There was no single building in ancient Greece where all twelve were worshiped; that only exists in Rome, which makes it ironic that the idea of a structure is a Roman construct onto a Greek idea, literally and figuratively. Since there was no such building until Roman times, but the word is solely of Greek origin, it is clear that there was no intention of a building until the Romans took over the "Pantheon" from the Greeks. Therefore, being a purist, I would never use this word to describe a building except for the sole named building in Italy. Ok, stepping off my soap box now.
Quickly, then in practice, it should refer to a small group of the best of a category. Nobel prize winners represent the pantheon of academic scholars. Senior partners meet as a pantheon of legal minds. The special publication of the pantheon of papers was widely regarded as a "must have" for every library. The seven wonders of the ancient world are a pantheon of the greatest structures ever built. Works with people, places, things, ideas, basically anything that has a "best" which is everything. I'll leave you to your own sarcasm about creating a pantheon of things which are less than the best, but you know mine would start with Plaintiff's counsel.