The only valid mystery at Baalbek is whether or not the Romans (and only the Romans) excavated and moved the trilithons which are a part of the temple
podium, or an earlier Canaanite/Phoenician people did it. "Ancient Aliens" theories are a complete scam designed to separate certain types of people
from their money.
I personally favor the idea that Tyrians under the aegis of Solomon were responsible for this phase of construction, since the podium at Baalbek
greatly resemble the style of the Great Temple at Jerusalem, also built by Solomon, and again relying on Tyrian workers.
Do some research on the Canaanites and especially the renowned stone masons and workers of Tyre. Tyre was fabled for it's great projects, which
included extending a harbor far out into the Mediterranean. The Baalbek podium adheres to the Canaan style of using only 3 levels or tiers, just as
the Jerusalem one does. The Canaanites were quite adept at cyclopean masonry construction as evidenced by the ancient cities Byblos, Sidon, and Tyre.
Modern scholars date the site of Byblos back at least 7,000 years. The Canaanites are the source of most of the myths (giants, etc.) that surround the
colossal stone work at Baalbek.
The site itself was of supreme religious importance to the Canaanites, as far back as pre-historic times. It became fabled as an oracle. The altar
became the nucleus around which the tell formed over the next several aeons (a tell being an ancient mound built up of detritus of continual human
occupation). By the time of Solomon this site was integral to the religious views of Canae.
See: DAI (German Archaeology Group)
...The oldest finds are dated by C14 analysis to the end of the Pre-Pottery Neolithic period around 7200 BCE. The settlement mound was only
abandoned in the late Hellenistic period due to its transformation into a monumental sanctuary and was settled almost continuously over a period of
nearly 7000 years. The architectural history of the relatively well-known sanctuary of Jupiter in the Qalaa is studied in detail since 2005. The
documentation of numerous archaeological and architectural features through soundings and measurements in combination with a new analysis of
constructional details have yielded a surprising wealth of new insights into the architectural layout and morphology of the sanctuary. As a result,
four monumental building phases can be distinguished: the buildings from the pre-roman period forming a gigantic T-shaped terrace, which was later
used as foundation of the temple of Jupiter, are now well understood in their dimension and geometry. Through new tachymetrical measurements in
the substructions of the Great Courtyard the planning and implementation of the extensive building program of the early imperial period can be easily
distinguished from later construction phases. Changes in the Great Courtyard and the construction of the so-called hexagonal courtyard in the middle
imperial period indicate two later changes in plan, which successively enlarged the sanctuary towards the east.
The inner podium then is what the trilithons belong to. The Romans then came in and extended this podium in three direction, north, east, and south,
leaving the western wall (and trilithons) alone (since it faced the downward facing slope). You can distinguish between the Roman efforts and earlier,
especially where the Romans used vaulting filled with rubble and the Canaan simply employed cyclopean masonry. Portions of the Roman extended wall
have collapsed, exposing these vaults, in fact a gift shop exists in one of them.
Additional facts regarding Solomon and the surviving western wall in Jerusalem with the Baalbek podium, to which they bear a striking resemblance;
THE EMBOSSED QUADERS
Aside from the incased trilithon, the attention of the visitor to Baalbek who inspects the wall of the acropolis is drawn to stones of a bossed shape
with an indented rim on all four sides of the face of the stone.
O. von Richter in 1822 60 and S. Wolcott in 1843 61 drew attention to the fact that the quaders of the wall of the temple area of the acropolis of
Baalbek have the same form as the quaders of the Temple of Solomon, namely, of the surviving western (outer) wall, or Wailing Wall. The Roman
architects, wrote Wolcott, never built foundations or walls of such stones; and of the Israelite period it is especially the age of Solomon that shows
this type of stone shaping (chiseling).
The photograph of the outer wall of Baalbek’s temple area illustrates that the same art of chiseling was employed in the preparation of stones for
its construction. Whatever the time of construction of other parts of Baalbek’s compound—neolithic, Israelite, Syrian, Greek, or Roman—this
fundamental part of the compound must have originated in the same century as the surviving (western) wall of the area of Solomon’s temple.
By the time the Romans arrived on the scene, Baalbek already had a lengthy history of temple construction. Trajan is credited with having initiated
the construction of the Temple of Jupiter, and was no doubt duly impressed with the sites history and reputation as an oracle, stretching back into
antiquity. There's not much else of a reason for him or his successors to build Rome's greatest temple in the middle of a remote backwater, which
was Baalbek. Today the temple of Bacchus is considered the greatest example of Roman temple construction still standing. One could only imagine how
much more magnificent the temple to Jupiter must have been.
With the eventual eradication of the Canaan/Phoenician culture, we've lost the reason why
this site was of such importance. Everyone from the
Egyptians, Hittites, to the Seleucid empire, seemed to hold this site in high regard.
Sorry if my post seemed a little off-topic, I happen to favor an earlier origin to the foundation construction at Baalbek than that of the Romans.
That doesn't mean that a mythological or extraterrestrial origin holds any water. You could use logic alone to destroy that notion...