You need one of those medical pokey camera thingies. ;)
But what about the "tenons", they wouldn't be man made surely?
You'll see. There is plenty of things not been noticed before because they haven't been looked for because it was considered a 'done and dusted' site. Once you suss it out it's surprising what you find and where things should really be instead of where they are now. Seek and you will find :-)