When, by whom, how, why? These questions will always be open to lots of opinions. We may never have exact answers, but slowly the science is helping. The dates are ok and fairly accurate. Not important to have an actual date, more important to learn about the type of society that existed at the time. How they were built, we have lost much of the ancient technology they must have used! We would struggle now to build using what they had available. My favourite question is why? Like the idea of a temple with multiple functions. Winter sunset, burial and worship of ancestors and other religious uses.