I had always wondered about the significance of the tree sculpture in front of Trinity Church in lower Manhattan so I decided to look into it. Here is some information I found on lowermanhattan.info.
Trinity Root is a bronze casting inspired by the remaining stump and root of a 70-year-old sycamore tree that shielded St. Paul's Chapel against falling debris during the collapse of the twin towers in 2001. In 2005, the finished three-ton sculpture was hoisted by a crane into the courtyard of Trinity Church. Visitors are able to walk through the sprawling root branches, which are 20 feet long, 15 feet wide, and 12.5 feet tall.