I participated in the Catalan Congress in 2015 in Mataró, where I caught up with an old friend, Jordi. When Clare and I did a holiday the following year through Spain, Catalonia and France the next year, we added Mataró as a destination and arranged to meet up with Jordi and his wife, Irina.
That was fun but what made it special was that he knew it was a special day in Catalonia; the festival of Sant Joan. Although on the face of it it sounds like this ought to be some sort of religious festival, in reality it seems more to do with fire and the fact that the night of the 23 June is the shortest night in the year. He'd arranged for us to meet in the centre of Mataró exactly where we would be close to the celebrations, which started when some representatives of the town arrived in the centre bearing a torch which had been lit on a special mountain somewhere else in Catalonia.
As an extra treat, he invited us to a special meal with his family and friends, and so we got to experience how the people in Catalonia celebrate the event, probably my favourite element being a special cake with some green sweets in it. (Sorry; I'll never wrap my tastebuds around the Catalan specialty of tomato smeared on a slice of bread!)
And on the way home, approaching midnight, we caught the firework display:
For that evening we were immersed in the most important national day in Catalonia, all because we spoke Esperanto. If we hadn't, we'd have been safely tucked up in bed, having missed the whole thing.