Lux Helsinki is a yearly based light-art festival happening in Helsinki during the darkest time of the year. It presents Finnish and international huge-scale outdoor artworks. I've been visiting this festival regularly for years. In the beginning, it was a rather small scale happening, but nowadays, it is a vast scale art festival. And because of free entrance, the number of audiences has increased a lot.
Lux Helsinki 2020 was worth visiting; I especially loved two pieces of artwork: Large Fire Tornado by Ivo Schoofs (NL) and Magic Mirror by Meri Ekola (Fin). You can read more about all artworks on Lux Helsinki website.