London’s Christmas tree in Trafalgar Square was lit up Thursday as part of a British tradition with roots in the Norwegian forest.

The tree symbolizes the friendship between London and Oslo in an annual ceremony that highlights the history of the countries’ alliance.

Billed on social media as “Britain’s national tree-sure,” the lighting ceremony signals the start of London’s countdown to Christmas and is traditionally held on the first Thursday in December.

Strings of lights hang vertically, following the Norwegian tradition.

The tree will remain in the square until Jan. 5, also known as the Twelfth Night of Christmas.

It will then be taken down to be chipped and composted for mulch.