Unification Day is a significant national holiday celebrated annually on September 6 in Bulgaria. It commemorates the unification of Eastern Rumelia and the Principality of Bulgaria, a pivotal moment in Bulgarian history, in 1885. The political movement unified two territories that were administratively split following the Treaty of Berlin, creating the contemporary state of Bulgaria we know today.

Despite its severe historical implications, Unification Day is widely celebrated with joy, enthusiasm, and a spirit of nationalism. The day's events usually involve massive ceremonies attended by state officials. Speeches are given, and a military parade is usually part of the festivities, promoting the unity and strength of Bulgaria as one nation. Many Bulgarians also celebrate with family gatherings, feasting, music, and fireworks.

However, the holiday represents more than just a historical event. It embodies the notion of unity and the importance of cohesiveness in a culturally diverse nation. It also stands as a key symbol of national identity, reminding Bulgarians of their shared history and collective strength. Unification Day holds an enduring significance in the hearts of many Bulgarians, and it continues to be a core part of the national cultural and historical heritage.