Yep, it was! Started in 1190 by the King Philippe Auguste to protect the fledgling city of Paris from invasion, the Louvre originally looked like the model above. Four-sided, with its rounded bastions and a moat, it must have looked quite a formidable sight standing on the banks of the river Seine.
So if you are visiting the Louvre and you want to see something other than the more popular paintings and sculptures, head to the Sully wing and go and see what's left of the old walls.
It's a relaxing place to visit - not many people make the effort - but I believe it's worth it. An added bonus, especially in the summer, is that it's very cool down here.
If you're a Mediaeval History geek or if you simply want more facts and figures, see the official website here.
Again, the opening hours for this attraction are the same as for the rest of the museum and access is included in the standard ticket. Free for EU 18-25s.