THE MYSTERY OF STONEHENGE

They have been many theories about who, how and why Stonehenge has been built, but because of our incredible new technology they are also some accurate facts, for example we know that it has been built in Britain in the neolithic, that the blue stones now in the midle were before around it, we also know the incredibly heavy weight of those stones and that they are some squelettin of neolithic people burried under Stonehenge. But the most incredible thing is that it forms a perfect circle and that on the winter solstice and on the summer solstice, the light go right through Stonehenge, cutting it in two!!! But the questions that make scientists go crazy are; How did they carry does rocks 20 feet tall and 25-40 tones ? How did they make it go in a nearly perfect circle without even having sketches? How did they calculate that the 2 solstices would go right through it? And why did they built it? As I said they are many theories including extraterrestrial's help and I will explain some of them.
Because they are so many questions to be answered, I will only share my research about the reason of Stonehenge. The first theory is that  Stonehenge has been built as a place for the dead, also for the ones alive to meet their ancestors but they also think it might have been a place to stop the illness. Some people also think that it might have been an observatory or even a place for UFO's to land on!!!
All of those theories are based on sources but are they true? Are we ever going to solve the mystery of Stonehenge?  Or is it going to stay a Mystery for ever?