NEW YORK (CBSNewYork/AP) — Mayor Bill de Blasio and first lady Chirlane McCray were on hand Saturday at the unveiling of a plaque marking the site of an 18th-century slave market in Lower Manhattan.

The plaque commemorates the open-air slave market that operated on Wall Street from 1711 to 1762.

“Let us remember today and everyday that a buying and selling of a people for profit and material gain took place right here,” McCray said.

First lady Chirlane McCray speaks during unveiling of Wall Street Slave Market plaque on June 27, 2015 (Credit: Roger Stern/1010 WINS)

First lady Chirlane McCray speaks during unveiling of Wall Street Slave Market plaque on June 27, 2015 (Credit: Roger Stern/1010 WINS)

During the dedication ceremony, de Blasio said slaves played a vital role in building New York City even though their time on earth “literally did not belong to them.”

“The concept of ‘We the People’ was undermined and sullied from the beginning by slavery. The quest to form a more perfect union was made imperfect by racism,” the mayor said.

Mayor Bill de Blasio looks at a new plaque marking the space where once stood the Wall Street Slave Market (Credit: Roger Stern/1010 WINS)

Mayor Bill de Blasio looks at a new plaque marking the space where once stood the Wall Street Slave Market (Credit: Roger Stern/1010 WINS)

De Blasio said that while equality is a foundation of our society, it is still not practiced today.

“The idea that all lives matter is a foundation of Democracy. It’s the foundation of everything that we consider to be our moral underpinning of our society, and yet, it still isn’t practiced,” he said.

McCray said it is important not to forget about slavery.

“If we want to create an even better New York we must grapple with the gruesome chapters of our past,” she said.

City Council member Jumaane Williams said New York was “built on the backs of slaves.”

The marker was first proposed by Christopher Cobb, a Brooklyn-based artist and writer.

The language on the plaque was prepared by the Parks Department and Landmarks Preservation Commission in collaboration with Christopher Moore, former director of research at the Schomburg Center for Black Culture.

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