I've been looking for this novel for years, I first read it in the late 1990s as a paperback. It was a mid-length novel, at least 200 pages.
It was about an archaeologist who was excavating an ancient site, possibly a temple. It was a prehistoric site, older than recorded history and there was some lost civilisation and I believe ancient aliens (or at least non-humans, I can't remember if they were from another planet or not) themes. The civilisation was either a fictional undiscovered one or linked to a very early one, BCE, as in not related to anything dark ages or medieval era. Edited to add: I believe the temple or site that was being excavated was more advanced than any other site from the ancient world. I'm thinking more advanced architecturally or engineering wise, as in monumental, huge. I feel like it was set in north Africa or the area we call the Middle East, possibly Turkey or around that part of the world. However, I believe the archaeologists were either European, maybe British or North American.
The archaeologist also had two students who were working with him, a young man and woman, who were experiencing dreams or reincarnation type memories of the site. I seem to remember a scene where these students are feeling "drawn" to the ancient site and are worried that their memories or visions are mental illness or hallucinations.
I feel like it was set around the time it was published [1980s or 90s?] or the near future, i.e. it wasn't particularly futuristic.
I borrowed it from my local library so I think it must have been a mainstreamish publisher. I really can't remember if it was intended for YA audiences or not, I feel it could have been written for mid-teens to adult audiences. Also gotta say I don't remember it being wildly well written or original or anything like that, it was a pretty decent novel with some interesting elements, but that's about it. I don't know why I want to find it again so badly, it's just been bugging me for years :)
I asked about this on another site (librarything) so can rule out novels written by Andre Norton, Michael Crichton and Pat Murphy.
Any leads or ideas would be very much appreciated! Thanks for your time :)