Stonehenge

If we don't know what it was, it's a "ritual object"! ;)
Jokes aside - I think it's quite safe to suppose that the builders of Stonehenge used "mythological" way of thinking and that religion was an integral part of their everyday life. We thus won't be wrong if we suppose there were some religious meanings of the site and actions performed on it. But we have to be careful in what do we imagine under those religious meanings - for the majority of todays people, religion invokes something a bit detached from everyday life, job and politics, something inner and spiritual. For the builders of Stonehenge those religious meanings were probably very much connected to everyday practical life and society.
They may have seen Stonehenge as extremely practical and useful thing...
The problem is that (if I remember it correctly), most of classical mythological themes we know from this part of the world are connected with the Iron age with some material maybe identifiable as Bronze age. And it seems there was quite a cultural change between the time of the builders of Stonehenge, and the late Bronze age and the Iron age from which we have at least some mythological material to speculate about. We think the society has changed (became more individualistic, as has been mentioned in the lectures). Perhaps the religious or mythological interpretation of the world changed too...