That's the western gate of Moria. The Nanduhirion map was made by EA and has simply been changed to work with the expansion plot building system of Edain 4. I think there were no visual changes made (and I don't think they'd be necessary).
Nanduhirion was NEVER in Bfme I.^^
It was made for Bfme II, I think it was only added for the addon.