[NOT A BUG] No Stoneworks building available

[FeiLing]

Game Version: 1.0.1.511

Marseille has an improved Marble resource within it's borders. It did/does receive the wonder production bonus of +15%. However Marseille is not able to build a Stoneworks.
No other city takes away the tile from Marseille, there's not even one in range.
Gotta have to do something with the water in between. It doesn't make any sense though.

Screenshot:

Spoiler :

Here the save game:
http://dl.dropbox.com/u/5773554/.Civ5Save_(GOTM & Bugs)/Stoneworks-Bug-Marseille.Civ5Save

 

[Optional]

It does look like Marseille is on a plains tile, though.

 

[FeiLing]

Damn it. Hate this requirement - doesn't make any sense. You gotta be right, no need to even look at the save file again. Guess I need to have a post it on my monitor that says "NEVER settle on damn plains!"