A virtual forest of trees will be one of the more distinctive features of the World Trade Center Memorial when it’s finished, and days ahead of the ninth anniversary of the 9/11 attacks, the trees have begun to arrive. Exactly 16 of them have been planted so far.

The trees are all swamp white oaks, and at the moment, they stand about 30 feet tall. In time, it’s possible they’ll reach a much more impressive 60 or 80 feet in height, however.

Also, it’s important to note that the initial 16 trees don’t represent a significant portion of the final target, which is in the neighborhood of 400 trees.

Then here’s one more interesting fact: Tina Moore reported, “The first of the trees come from New York, Pennsylvania and Washington – the locations of the three attacks.”

All of the trees should remain healthy regardless of weather conditions, as underground tubes will supply them with water and fertilizer. Digital sensors should provide groundskeepers with updates, too, in case any of the trees need extra care.