In Spain Constitution Day is a national holiday. Its official celebration is on December 6th, but as it’s Sunday it’s observed on Monday 7th.
Although local government or schools do not open, most shops do, so it’s the perfect opportunity to begin Christmas shopping.
This day commemorates the referendum of 1978 in which the Spanish people approved the current constitution by a large majority. The week before, schools perform different events, and on the 6th, public institutions hold the official celebration.