Having left booking my flight very late, I ended up with a 10 hour stopover in Madrid. Fortunately this was from lunchtime to late in the evening, so ideal to see Madrid's Christmas Markets and attractive Christmas lights.
I can't say the Christmas Markets compared with those in Germany or Belgium, but Plaza Mayor had vast numbers of stalls with nativity figures (a bit like santons, but in different sizes and styles). It also had these street performers dressed up as tinsel-covered goat-like snapping-mouth creatures which I recall seeing before in Cangas (do they have a name?)
It was a bit chilly, but still nice enough to walk in one of the parks before the sun set. After a three-course meal + a beer for under 10 Euro, I headed back to the airport.