In 2002, planning began for a new World Trade Center. The planning was not just to replace the fallen icon, but to memorialize it. The process began with a number open design competitions.
http://robertgillingswtcdesign.com/2017/07/robert-gillings-on-one-world-trade-center-development-and-features/
http://robertgillingswtcdesign.com/2017/07/robert-gillings-on-one-world-trade-center-development-and-features/