Which of the following is a man-made structure?

I've not been to the Great wall of china

little b, go, it's amaze!

little b, you should go!

little b, me neither… it was built well to last all these years n for so many of us to visit the site where it starts… I enjoy history now that I’m older.

if their is anything you want to know about it just ask

little b, neither have I, but I know a lot about it