Robert Moskowitz, a painter who used the New York City skyline as his muse for work that borders abstraction and representation, died on March 24 in Manhattan. He was 88.

Beginning in the 1970s, Mr. Moskowitz began painting the Empire State Building, the Flatiron Building and, most indelibly, the World Trade Center. Those three buildings appear over and again through the decades, ink black on blue, lavender, orange, yellow or white; in white on black; surrounded by smudgy fingerprints or plumes of smoke; naked in fields of color; rendered in oil, ink, graphite or pastel.

But it was in the imposing modernist stripes of the Twin Towers that Mr. Moskowitz found his great subject, The New York Times said. After the attacks of Sept. 11, 2001, these works took on a darker resonance, and Mr. Moskowitz, whose TriBeCa loft was only a few blocks from the towers, regretfully moved on to other motifs.

The throughline of his career was always his devotion to his art. “All he did was paint,” said the sculptor John Newman, a longtime friend. “It’s all he wanted to do. And when he couldn’t paint, he drove a cab so he could paint some more.”