Yesterday was the date of an important topping out ceremony in New York, as the new "One World Trade Centre" ceremonially reached its highest point.
I happened to attend another Manhattan topping out ceremony on the same day, a little further uptown. I joined a group celebrating the highest point of a new social housing block in Harlem by watching a tree be planted on top of the unfinished building.
Apparently this practice is Scandinavian in origin, with references to the Vikings performing similar ceremonies as early as 700 AD. Some sources attribute the ceremony in its current form to the Vikings. Others claim this early practice of topping out involved not trees but sheaves of grain (to feed Odin's eight-legged horse, Sleipnir), and that this was adapted by pre-Christian, tree worshiping Europeans, with a tree placed at the top of a new structure to appease any spirits displaced in the activity of building.
Sleipnir in Odin Rides to Hell (1908) by W. G. Collingwood. Source: Wikimedia Commons
The spirituality of trees was historically celebrated all across Europe. Celtic (such as the Gauls and Britons) and Germanic tribes (such as the Angles, Saxon and Jutes, as well as the Norse) all recognised spirits residing in trees, and many of these customs remain. You can read more about the place of tree worship in modern Europe, particularly in association with the celebration of May Day, in Chapter 10 of James Frazer's The Golden Bough.
A Jack-in-the-green ceremony in Hastings, England. Source: Properganda
Although Harlem - particularly the Sugar Hill area to the North, where we were - is surprisingly green, it's unlikely any trees were felled when this steel-and-concrete building took the place of an early 20th century garage. Yet the tradition endures. The tree now symbolises growth and sustainability, and promises good luck for the building's future residents.