The Anniversary of the 'Arengo' is a significant holiday in San Marino, a small republic surrounded by Italy. The 'Arengo' was a form of government that was prominent in San Marino during the Middle Ages till 1243. On this day, the citizens of this ancient republic commemorate the formation of this unique governmental system.

The holiday represents a pivotal moment in the history of San Marino. The Arengo era was characterized by a socio-political structure dominated by family heads who made decisions based on majority vote. However, over time, the system became corrupt, leading to the transition to the 'Captains Regent' system, which is still in place today. The 'Arengo' is remembered as a symbol of unity and democratic ideals.

Besides its historical significance, the Anniversary of the 'Arengo' also provides an excellent opportunity for unity and taking pride in the rich heritage of San Marino. Local communities organize various activities that reflect the customs and traditions from that era. Some of the highlights include parades featuring period costumes, historical re-enactments, and cultural exhibitions. It's a day when people not only celebrate their past but also pledged to uphold the spirit and ideals of the 'Arengo'.