New York ? In an exhibit full of beautiful black-and-white photographs, historical blueprints and an 18-minute video, one piece dominates: an architectural model of the World Trade Center in which the twin towers are 7 feet tall.

The model is the only one left in the world. Two others were destroyed when the towers collapsed.

A sunrise picture made in 1973, left, shows an X-ray

Now, it is the centerpiece of “WTC: Monument,” an exhibit at The New York Historical Society. The show, which opened this month, focuses more on the creation of the trade center in the late 1960s and early 1970s than its destruction on Sept. 11.

“These represent the culmination of the evolution of the history of size in buildings. We arguably have built taller buildings … but we never built them larger,” said Carol Willis, director of The Skyscraper Museum, which is presenting the exhibit with the historical society.

The exhibit got its start before the terrorist attacks, when Willis decided The Skyscraper Museum should hold a series of public programs about the trade center to commemorate its 30th anniversary and to mark its transfer from the public ownership of the Port Authority to a private leaseholder.

The first event was scheduled for October at the trade center’s Windows on the World restaurant.

After Sept. 11, The Skyscraper Museum found itself without a home its temporary gallery in lower Manhattan was off-limits and with a whole new mission.

The first part of the exhibit focuses on the challenges faced by lower Manhattan in the mid-20th century. Crowded with buildings constructed before the Depression and hemmed in by little-used piers, it was losing business and corporate headquarters to midtown Manhattan.

The second part of the exhibit details the planning and construction of the World Trade Center and Battery Park City, the nearby residential area created in part with dirt from the trade center’s excavation. It features blueprints, a video about the building of the towers and magazine articles from the time celebrating the architectural and engineering advances of the trade center.

The final part of the exhibit touches on Sept. 11, through the front pages of 15 newspapers the next day and four photos, measuring 5 feet by 9 feet, taken by George Peterson, a still-life photographer working in his studio about 2 miles from the twin towers.

Willis said she hopes the exhibit gives hope to New Yorkers that lower Manhattan will recover from the terrorist attacks, just as it dealt with earlier challenges.

“If you look at New York in the 1960s, you see a city trapped in a sort of physical harness of the past that needed to catch up to its present. Now we’ve had a new present thrust upon us and we need to adjust and figure out the needs of the 21st century,” she said. “It’s the nature of cities to rebuild.”

The exhibit runs through May 5.