Christianfeast day:

Abercius and Helena, Alcuin of York, Aurea of Ostia, Austregisilus, Baudilus, Bernardino of Siena, Ivo of Chartres, Lucifer of Cagliari, Sanctan, May 20 (Eastern Orthodox liturgics)

An Eastern Orthodox liturgical feast commemorating saints such as Abercius and Helena on May 20.
May 20 in the Eastern Orthodox Church is dedicated to commemorating Abercius and Helena, along with a host of other saints including Alcuin of York, Aurea of Ostia, and Lucifer of Cagliari. These feast days honor their faith, teachings, and sacrifices in the early Christian church. Services feature hymns, prayers, and readings that reflect on each saint's life and spiritual legacy. The observance connects believers with centuries-old traditions and deepens communal worship.
feast day Abercius and Helena Alcuin of York Aurea of Ostia Austregisilus Baudilus Bernardino of Siena Ivo of Chartres Lucifer of Cagliari Sanctan May 20 (Eastern Orthodox liturgics)

Day of Remembrance (Cambodia)

A Cambodian national holiday honoring the victims of the Khmer Rouge regime.
Observed annually on May 20, Cambodia’s Day of Remembrance pays tribute to the millions who perished under the Khmer Rouge between 1975 and 1979. Official ceremonies are held at memorial sites such as Choeung Ek, where survivors and families lay flowers and light candles. The day fosters national healing by teaching younger generations about this tragic chapter in history. Educational programs and moments of silence ensure that the stories of victims are never forgotten.
Day of Remembrance (Cambodia)

Emancipation Day (Florida)

A Florida state holiday commemorating the emancipation of enslaved people in 1865.
Emancipation Day in Florida marks May 20, 1865, when Union forces arrived in Tallahassee and informed enslaved African Americans of their freedom. Observed as a state holiday, it features parades, educational events, and ceremonies that honor the resilience and contributions of the African American community. Schools and organizations hold discussions on civil rights and the ongoing struggle for equality. The day serves as a reminder of the journey from slavery to freedom and the importance of continuing the fight for justice.
Emancipation Day (Florida)

European Maritime Day(European Council)

European Union observance highlighting the importance of maritime activities for trade and economy.
European Maritime Day is celebrated annually on May 20 to emphasize the maritime sector’s contribution to the EU’s prosperity and connectivity. Organized by the European Commission, the day features conferences, workshops, and networking sessions that address sustainable shipping, marine research, and Blue Growth strategies. Stakeholders from industry, academia, and government gather to discuss policies that support maritime innovation and environmental protection. The event fosters cooperation across member states and promotes the sea’s role in global trade and cultural exchange.
European Maritime Day European Council

Independence Restoration Day, celebrates the independence ofEast TimorfromIndonesiain 2002.

East Timor’s holiday marking restoration of its independence from Indonesia in 2002.
Independence Restoration Day, observed on May 20, celebrates East Timor regaining its sovereignty after years of Indonesian occupation. Following a UN-supervised referendum in 1999 and transitional administration, East Timor officially became independent in 2002. The holiday features flag-raising ceremonies, cultural performances, and official speeches in Dili and across the country. Citizens reflect on their struggle for freedom and honor those who fought for national self-determination. The day reinforces national pride and unity in one of the world’s youngest nations.
Independence Restoration Day East Timor Indonesia

Josephine Baker Day(NAACP)

NAACP commemorative day honoring Josephine Baker’s legacy as an entertainer and civil rights activist.
Josephine Baker Day, observed by the NAACP on May 20, celebrates the life and achievements of Josephine Baker, famed dancer, singer, and entertainer who broke racial barriers in the 20th century. Born in 1906 in St. Louis, Baker rose to international stardom in Paris and used her platform to fight for civil rights in the United States. The day features cultural events, panel discussions, and performances that highlight Baker’s artistic contributions and her work with the NAACP. It honors her pioneering spirit, advocacy for equality, and lasting impact on arts and social justice.
Josephine Baker Day NAACP

National Awakening Day(Indonesia), and its related observances:

Indonesian Doctor Day(Indonesia)

In Indonesia, May 20 honors the 1908 National Awakening movement and also celebrates Indonesian Doctor Day.
National Awakening Day commemorates the founding of Budi Utomo on May 20, 1908, widely recognized as the beginning of Indonesia’s organized nationalist movement. The day features educational programs, flag-raising ceremonies, and cultural performances that celebrate Indonesia’s unity and independence efforts. Relatedly, Indonesian Doctor Day acknowledges the vital role of physicians in public health, with seminars and health campaigns nationwide. Together, these observances highlight Indonesia’s journey toward self-determination and the continued importance of healthcare in society.
National Awakening Day Indonesia Indonesian Doctor Day

National Day (Cameroon)

Cameroon’s Unity Day celebrates the national reunification achieved on May 20, 1972.
National Day in Cameroon, observed on May 20, marks the reunification of British Southern Cameroons with French Cameroon following a 1972 national referendum. The holiday includes colorful parades, presidential addresses, and cultural festivals that showcase Cameroon’s diverse heritage. Military displays and civic gatherings are held in Yaoundé and other regions, fostering national pride and solidarity. Citizens reflect on the significance of unity in building a stable, prosperous nation.
National Day (Cameroon)

World Bee Day

United Nations day to raise awareness about the crucial role of bees in ecosystems and agriculture.
World Bee Day, established by the UN in 2017 and celebrated on May 20, highlights the importance of bees and other pollinators for ecosystems, food security, and biodiversity. The date honors the birthday of Anton Janša, a pioneer of modern beekeeping. Events worldwide include educational workshops, beekeeping demonstrations, and campaigns against pesticide use. The observance encourages community action to protect pollinator habitats, promote sustainable agriculture, and support scientific research.
World Bee Day

World Metrology Day

Annual international observance celebrating the science of measurement and global metrological cooperation.
World Metrology Day on May 20 commemorates the anniversary of the signing of the Metre Convention in 1875, which established the International Bureau of Weights and Measures. The day promotes the importance of measurement standards in science, industry, trade, and daily life. Each year features a theme highlighting developments such as digitalization of measurements or climate research. Workshops, seminars, and exhibitions are held by metrology institutes worldwide to showcase innovations and encourage collaboration.
World Metrology Day

Abercius and Helena

An Eastern Orthodox feast honoring Saints Abercius and Helena, early Christian martyrs.
The Orthodox Church commemorates Saints Abercius and Helena on this day, celebrating their unwavering faith in the early centuries of Christianity. Saint Abercius, a bishop known for his missionary work and inscriptions at Hierapolis, and his sister Helena are venerated for their steadfast witness during periods of persecution. Worship services include readings of their hagiographies, hymns, and prayers invoking their intercession. Icons depicting the pair emphasize their spiritual legacy and familial bond. Across Orthodox communities, believers reflect on the power of faith and the example set by these early martyrs.
Abercius and Helena

Alcuin of York

Feast day of Alcuin of York, celebrated for his scholarship and leadership during the Carolingian Renaissance.
Alcuin of York was an 8th-century Anglo-Saxon scholar and teacher who became a key figure at Charlemagne's court. His writings and guidance were instrumental in the Carolingian Renaissance, shaping medieval education and theology. Known for his letters, poems, and reform of monastic schools, Alcuin promoted learning across the empire. On his feast day, churches reflect on his intellectual legacy and the enduring value of education. The day often includes readings from his works, lectures on his contributions, and veneration in liturgy. Alcuin's life reminds believers of the harmony between faith and reason.
Alcuin of York