Afterfeast of The Elevation of the Holy Cross - 09/19/21
One of the 12 Great Feast Days in the Liturgical year.
The day of the Elevation of the Cross became, as it were, the national holiday of the Eastern Christian Empire, similar to the Fourth of July in the United States.
Read more at https://www.oca.org/orthodoxy/the-orthodox-faith/worship/the-church-year/elevation-of-the-cross