Sky Castle

Well basically, it's a lot like a very traditional and historically correct version of Santa-clause.
We don't get presents with christmas (well traditionally we don't, nowadays a lot of families do, specially when the kids are older, but that's just blown over form neighboring countries and the US), we get them 20 days earlier instead.
Every year in the middle of November, Sinterklaas arrives in the Netherlands. He lives in Spain all year long, but comes here to celebrate his birthday at december 5th. He arrives on a steamship with his helpers, who are called black Piets (yes all of them are called Piet *laughs*). He's always welcomed by lots of kids standing in the haven singing songs. From there on, he goes on his white horse.
In the three weeks following, he and his helpers go on the roofs and the Black Piets slide down trough chimneys. Kids put their shoes in front of the hearts and sing a song before going to sleep and when they wake up they find a small present or some candy(but only if they've been good of course). That happens about twice a week.
Than, at the 5th of december, when the man has his birthday, there's parties everywhere. Sinterklaas and his Piets come to the kids schools (magically to all of them of course :P) and in the evenings, a sack filled with presents is brought to the children's homes. Often, parents ask a neighbor to put it in front of the door and knock and generally make a lot of noise before disappearing, or ask a friend to play Sinterklaas or black Piet. My brother played black Piet for the kids I babysit this saturday, and I will be doing so for my fosterbrothers tonight, along with a friend. Back Piet is generally happy, cheerful and mischievous. We give out the presents and than go.
After unpacking all of the presents, the small children go to bed. Often, the older children and adults also exchange gifts, but they do it in the form of surprises; everyone gets one person to buy a present for and they make a trickpresent for that person, mainly something to make fun of the person (I made my dad a book with the hardest text I could find in the university library with the story that if he learned all that, Sinterklaas would take him to Spain next year and he could be the misunderstood genius Piet because he's always so sure he is right and noone agrees). We make a poem with it and than exchange the gifts.

Basically, Sinterklaas (Santa Claus is basically how you'd translate it in English) was a Spanish bisshop who spend the fortune he inherited on giving out gifts to poor people on his birthday. The black Piets are historically slaves who helped him do that, though little kids don't pick up on that of course. It's all in all a very cheerful, happy festivity and I enjoy it a LOT.