A thought

Have you ever wondered where the ancient cities and their building came from? Many have. It seems there are 3 different ideas. Aliens from outer space, the cave man, and man shortly after the creation. If these things were built by aliens where did they go and why did they not leave us a better record? If they were built by cave man or early man where did they get the intelligence to do this? We have a difficult time figuring how it could have been done so well without our modern tools. However if it was shortly after the creation and God created man perfect, He also gave them great intelligence and they must have know a lot of things that we have figured out in the last couple hundred years or less. I prefer to think that man was created with great intelligence and we regressed and have only lately figured out how to do some of these things.