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Now that Christmas is over, it is time to dispose of the Christmas tree that you bought. Fortunately, as easy as it was to purchase a tree, it is also easy to dispose of the trees, free of charge. There are over 500 collection points around the city and trees can be dropped off until 12 January 2020 at them.
Check out https://www.wien.gv.at/umwelt/ma48/sauberestadt/christbaumsammlung/ for a map to see where your nearest collection point is.