This fiesta takes place all over Spain and has been celebrated since 1978, after the death of Franco, when democracy was introduced to Spain. In Spanish Day of the Spanish Constitution is “el Día de la Constitución Española” and it means a day off work for the Spanish and Canarians.
On mainland Spain this fiesta isn’t actually a big deal. It doesn’t seem to be celebrated that much. The same applies in the Canaries. You might see some flags flying and wonder why half the local shops are shut but that’s about it! 🙂
It’s a bank holiday but not one of the big ones.