The overall height of the towers will likely be from 13 to 20 stories high (138 feet to 208 feet), large enough to convey the original towers' mass, although they could even be higher. The ultimate height will be determined by and proportionate with the immediate environment (neighboring buildings, etc.). The memorial's plaza may be as large as the WTC plaza that was destroyed on September 11th. The following images are based on 20-story towers. For example, the columns supporting the lower pentagon pool would be around 14 feet high.