Munich-based gold dealer Pro Aurum made the Christmas tree out of gold coins. They've dubbed it "the most expensive Christmas tree in Europe. With it being valued at $2.6 million, I don't doubt them.
"The “tree” stands 3 meters tall and weighs in at 63 kilograms of pure gold. That translates to 138.891 pounds – approximately. It features 2,018 solid gold one-ounce Vienna Philharmonic coins, topped by a massive 20-ounce coin, placed into a golden star." - in Schiff Gold