Picea abies outside of its native range, and one of the most economically important coniferous species in Europe. It is used as an ornamental tree in parks and gardens. It is also widely planted for use as a Christmas tree. Every Christmas, the Norwegian capital city, Oslo, provides the cities of London (the Trafalgar Square Christmas tree), Edinburgh and Washington D.C. with a Norway spruce, which is placed at the most central square of each city. This is mainly a sign of gratitude for the aid these countries gave during the Second World War. In North America, Norway spruce is widely planted,
Aristotelous Square Following Greek traditions, apart from a Christmas tree, the municipality of Thessaloniki also decorates a giant "Christmas ship", which is a Greek variant of the custom of decorating a Christmas tree. Both the Christmas tree and the Christmas boat are over 20 meters tall and are considered a tourist attraction for visitors to the city at the time they are up. Since its creation, the square has been used for a number of important party rallies. Many former Prime Ministers of Greece have given their main address from Aristotelous Square, including Andreas Papandreou, Costas Karamanlis and George Papandreou. Apart from