A sagging economy diminished the need for office space. Construction progressed in fits and starts through 2009. Nevertheless, the new World Trade Center began to take shape. The concrete and steel core of 1 World Trade Center (Freedom Tower) rose, and Tower 4 was well underway. In August 2009, a final symbolic beam from the Ground Zero debris was returned to the World Trade Center site where it could become part of the Memorial Museum Pavilion. By the summer of 2010, all of the steel supports were installed and most of the concrete was poured. In August, the first of the planned 400 new trees were planted on the cobblestone plaza surrounding the two memorial pools.
