Kingdom Day is celebrated on 15 December, the day on which Queen Juliana signed the Charter for the Kingdom in the Hall of Knights in 1954. Kingdom Day is not an official public holiday.
At that time the Kingdom of the Netherlands was made up of the Netherlands, Suriname and the Netherlands Antilles. Today, the Kingdom comprises four countries: the Netherlands, Aruba, Curaçao and St Maarten.
In 2008 Naturalisation Day, when naturalisation ceremonies take place for new Dutch nationals, was also moved to 15 December. On Kingdom Day, the Dutch flag is flown outside all central government buildings.