Silverstein separated from his business partner, Bernard Mendik, in 1977, and bought a number of large office buildings in Midtown and Lower Manhattan in the late 1970s.

[11] In 1991, he set aside 20 floors of 120 Wall Street to be leased by non-profit organizations, as an Association Center, with tax incentives for the tenants and bonds for Silverstein to undertake building renovations.

[15] In 1980, Silverstein won a bid to lease and develop the last undeveloped parcel from the Port Authority of New York and New Jersey, to build the 47-story 7 World Trade Center.

During the 1990s, New York was suffering from the effects of the 1987 stock market crash, which led to high vacancy rates at the World Trade Center.

George Pataki became Governor of New York in 1995 on a campaign of cutting costs, including privatizing the World Trade Center.

A sale of the property was considered too complex, so it was decided by the Port Authority to open a 99-year lease to competitive bidding.

[27][28] The jury was unable to reach a verdict on one insurer, Swiss Reinsurance, at that time, but did so several days later on May 3, 2004, finding that the company was also subject to the "one-occurrence" interpretation.

[30] The second trial resulted in a verdict on December 6, 2004, that nine insurers were subject to the "two occurrences" interpretation and, therefore, liable for a maximum of double the face value of those particular policies ($2.2 billion).

This litigation was settled, together with the federal lawsuits and appraisal (described in the prior paragraph), in a series of settlements announced on May 23, 2007.

[33][34][35][36] Silverstein's lease with the Port Authority for the World Trade Center complex requires him to continue paying $102 million annually in base rent.

While the site remains unoccupied, he continues to pay $10 million per month in rent to the Port Authority of New York and New Jersey.

After the September 11 attacks, the United States Congress approved $8 billion in tax-exempt Liberty Bonds to fund development in the private sector at lower-than-market interest rates.

In April 2006, after several months of negotiation aimed toward permitting reconstruction to commence, Silverstein yielded some of his rights back to the Port Authority to facilitate rebuilding at the site.

[47] Among his residential projects is an extensive complex that takes up the entire block between 42nd and 41st Street and between 11th and 12th Avenue in the Hell's Kitchen neighborhood.

[52] The building, the tallest residential tower downtown, designed by Robert A. M. Stern and marketed as 30 Park Place, officially opened on October 5, 2016.

[53][54][55] He sold his previous apartment, custom designed by James Stewart Polshek at 500 Park Avenue, in January 2019.

It was the first of five towers to open at the new Riverside Center megadevelopment on Manhattan's far West Side, which Silverstein developed in partnership with the Elad Group.

[58] In 1989 Silverstein proposed to members of the Israeli government that a free trade zone should be created within the Negev region of Israel.

Silverstein surprised Klara with the gift after she gave her farewell remarks as chairwoman of the Hunter College Foundation board of directors.

[61][62] That same year, he and Klara donated $5.25 million to New York University School of Medicine to create the Silverstein Scholarship Fund.