season

@Marion: it's a large valley in upper Wallis (Switzerland) and the Swiss do a lot of that skiing in winter.
The building you see in the background is where the army planes are parked... they go inside those structures and an elevator brings them down below the ground.... Switzerland mountains are like a big "gruyere" cheese, you know the cheese with holes in it ! ;-)

@maxine: yes, they are very concentrated ! ;-)