What is the setting of A Soldier of the Great War by Mark Helprin?

The temporal setting of the novel is twofold - the present as Alessandro leads a young companion on a mountain hike, and the period of World War I when he himself was a young man who fought as a soldier in the Italian army against Germans and Austrians. The physical setting begins in contemporary Rome and shifts throughout the story according to Alessandro's travels: Venice, Munich, Bologna, Sicily, Stella Maris, the Apennine Mountains.