It is today. It is the longest day of the year -- in reality the longest day was a couple of days ago, but today is officially celebrated as the longest day of the year.
As far as I know, the Midsummer Eve is celebrated only in Scandinavia and the Baltic region, and in a lesser degree in Germany, France and -- where else?
It is traditionally also a drinking festival, but it has not meant anything like that to me for almost five decades.
Many people go to the countryside and cities look peaceful and empty. It is a fine archaic festival, especially now that the sky is cloudless and the weather is warm.
And the night is very long!