Monday is Labor Day in the US. Officially this national holiday honors the American Labor force, on a lighter note, it marks the end of summer and back to school for kids.
If you need to contact the consulate or embassy, remember that the holiday is respected in US facilities abroad too.
On the other hand if you just want to call a friend, remember that he is probably at a family cookout or just enjoying the long weekend with his family!
Don't worry... in Trieste we'll be hard at work on Monday.