Holidays of Bulgaria - Day of Equal-to-the-Apostles Tsar Constantine and his mother Queen Helena
Celebrated on 21 MayHolidays of Bulgaria - Day of Equal-to-the-Apostles Tsar Constantine and his mother Queen Helena
Other holidays on 21 May
- UN Holidays - International Tea Day
- International holidays - International Space Day
- UN holidays - World Day for Cultural Diversity for Dialogue and Development
- Russian Holidays - Polar Explorer Day
- Russian Holidays - Military Translator Day
- Russian Holidays - Day of the Pacific Fleet of the Russian Navy
- Funny Holidays - World Rose Day
- Russian holidays - Unemployment Protection Day
- Russian holidays - BTI Workers' Day (Inventory Day)
- Holidays of Kazakhstan - Day of Workers of Culture and Art
- Holidays in Bulgaria - Predoj
- Holidays of Montenegro - Independence Day
- Holidays of Greece - Pirovassia (fire walking) (Anastenaria)
- Day of Remembrance for the Victims of the Caucasian War in Abkhazia (Circassian Day of Mourning)
- According to the folk calendar - Ivan the Dolgy
- Memorial Day of St. John the Evangelist (patron saint of authors, editors and publishers)
- Memorial Day of St. Arseny the Great