Great Union Day, celebrated on March 1st, marks the unification of the Moldavian Principality and the Wallachian Principality in 1859. This event is significant in the history of Romania, as it laid the foundation for the modern Romanian state. The day symbolizes the desire for national unity and independence. The celebration includes various activities such as parades, cultural events, and speeches that honor the historical importance of the union. It serves as a reminder of the efforts made by leaders like Alexandru Ioan Cuza, who played a crucial role in the unification process.