Kingdom Day (Netherlands), moves to December 16 if the 15th is on a Sunday

Koninkrijksdag is the commemoration of the signing of the Charter for the Kingdom of the Netherlands on 15 December 1954 in Aruba, Curaçao, the Netherlands, and Sint Maarten. When 15 December falls on a Sunday, the commemoration takes place on Monday 16 December. Kingdom Day is, unlike Koningsdag, not an official national holiday, but government buildings are instructed to fly the flag of the Netherlands.

The Netherlands, informally Holland, is a country in Northwestern Europe, with overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Netherlands. The Netherlands consists of twelve provinces; it borders Germany to the east and Belgium to the south, with a North Sea coastline to the north and west. It shares maritime borders with the United Kingdom, Germany, and Belgium. The official language is Dutch, with West Frisian as a secondary official language in the province of Friesland. Dutch, English, and Papiamento are official in the Caribbean territories. People from the Netherlands are referred to as Dutch.