1960: The World Trade Center (WTC) was initiated by a Lower Manhattan Association created and chaired by David Rockefeller, who had the original idea of building the Center with strong backing from the then New York governor, his brother, Nelson Rockefeller.

The World Trade Center

Ground Breaking Ceremony August 5, 1966

Height: 1,368 and 1,362 feet (417 and 415 meters)

Owners: Port Authority of New York and New Jersey

Architect: Minoru Yamasaki, Emery Roth and Sons consulting

Engineer: John Skilling and Leslie Robertson of Worthington, Skilling, Helle and Jackson

Opening Ribbon Cutting April 4, 1973

Design:

Note the conventional construction of the massive steel core. "Essentially, each tower was a box within a box, joined by horizontal trusses at each floor. The outer box, measuring 208 feet by 208 feet (63x63 m), was made up of 14-inch (36-cm) wide steel columns, 59 per building face, spaced just over 3 feet (1 m) apart. .... The columns were covered with aluminum, giving the towers a distinctive silver color. The inner box at the core of each tower measured about 135 feet by 85 feet (41x26 m). Its 47 heavy steel columns surrounded a large open area housing elevators, stairwells and restrooms."

The core structure is on the left. The peripheral floor is on the right:

The core and peripheriphy contrasted by sunlight passing through the building:

1980 November: Larry Silverstein wins a bid to lease and develop the last undeveloped parcel from the Port Authority of New York and New Jersey to build 47-story 7 World Trade Center (WTC 7).