Thank you so much for all of this great info, @Francisco! Your altar looks gorgeous- I love the inclusion of summertime flowers and fruits 
A fun fact for everyone- we have a local Summer Solstice celebration here in Poland! The festival is called “Wianki” (wreaths) and it is a celebration of the Slavic pagan goddess Kupala- a Slavic deity of love and the harvest.
The ceremonies include floating wreaths down a river 
and jumping over bonfires 
. If anyone is interested in learning more about Wianki, a good website is here!
From what I can find, it looks like the city of Krakow will celebrate Wianki online this year due to the current pandemic situation. Even in times of uncertainty, it is possible to celebrate and honor ancient traditions! 