We're hoping that today is the day everyone puts up their decorations, so we can have some photos of interiors and exteriors that make us go wow! Do send us your snaps!
A round-up today of some of the other Advent Calendars you can access online - these will get you thinking and puzzling.
The first one is from the NRICH webiste - it has 24 different maths puzzles to try, some are games you experiment with online.
Their sister website PlusMaths has a set of Wild Maths activities to encourage creativity. Give them a go, but like this calendar, you can't click ahead, so keep visiting!
And finally for today, Chalkdust Magazine, a new publication for Maths fans, has a set of instructions for some Christ-mathsy crafts, like the Flexagon above.