This is a Christmas tree standing on the Dam in Amsterdam. Every year a tree is put there. The habbit of using Christmas trees dates from ages back.
With likely origins in European pre-Christian cultures, the Christmas tree has gained an extensive history and become a common sight during the winter season in various countries.
Patron trees (for example, the Irminsul, Thor's Oak and the figurative Yggdrasil) held special significance for the ancient Germanic tribes, appearing throughout historic accounts as sacred symbols and objects. According to Adam of Bremen, in Scandinavia the Germanic pagan kings sacrificed nine males (the number nine is a significant number in Norse mythology) of each species at the sacred groves every ninth year.
Tradition credits Saint Boniface with the invention of the Christmas tree. The Oak of Thor at Geismar was chopped down by Boniface in a stage-managed confrontation with the old gods and local heathen tribes. A fir tree growing in the roots of the Oak was claimed by Boniface as a new symbol. "This humble tree's wood is used to build your homes: let Christ be at the centre of your households. Its leaves remain evergreen in the darkest days: let Christ be your constant light. Its boughs reach out to embrace and its top points to heaven: let Christ be your Comfort and Guide." (text taken from Wikipedia)
Also Santa has a strong connection and long tradition with Christmas. Numerous parallels have been drawn between Santa Claus and the figure of Odin, a major god amongst the Germanic peoples prior to their Christianization. Since many of these elements are unrelated to Christianity, there are theories regarding the pagan origins of various customs of the holiday stemming from areas where the Germanic peoples were Christianized and retained elements of their indigenous traditions, surviving in various forms into modern depictions of Santa Claus.
And the return of the (sun)ligth (solstice) has to do with putting lamps in the tree and even burn them lateron. Worldwide, interpretation of the event has varied from culture to culture, but most cultures have held a recognition of rebirth, involving holidays, festivals, gatherings, rituals or other celebrations around that time.