John Noble (who plays Walter) is also Australian (not British). He also played Denethor in The Return Of The King (if they had written that role closer to the character in the book it would have done much more justice to his talents). All the actors in Fringe do a fine job but he's outstanding - he displays enormous range and subtlety.

NEVER EAT while watching Fringe

Me too, love all the behind the scenes.

To answer your question, the show was filmed AFTER the September 11 attacks (which were in 2001.) The twin towers were only the two largest buildings of a larger complex. There were 7 buildings in total, two which were directly struck. One other collapsed in the immediate aftermath and the rest were eventually condemned and demolished due to extreme damage and contamination of toxic debris/smoke.