[Photos by Wil Blanche via National Archives. All captions are the 1973 originals.]

The tallest tower of the new World Trade Center reached its full height last week, 40 years after the Twin Towers opened as the original WTC. At that time, the Environmental Protection Agency hired photographer Wil Blanche to document the new giants and the changing Financial District. The Atlantic Cities recently highlighted the photos, which were taken in May 1973 as part of the Documerica project, a visual exploration of environmental issues around the country. The National Archives shared 87 of Blanche’s historic photos onFlickr, and we chose 18 to include in the gallery above.

18 Photos of FiDi When the Twin Towers Were the New WTC – Sepia Tones – Curbed NY.