PITTSBURGH — More than 50 years ago, Nicholas Parrendo designed stained-glass windows for the Tree of Life congregation in Pittsburgh's Squirrel Hill neighborhood.

Now his children, David and Celeste, along with artisans and master glaziers at Hunt Stained Glass Studios, are restoring them for the synagogue, the site of America's worst antisemitic attack in 2018.

It's part of a planned renovation of parts of the Tree of Life grounds. Daniel Libeskind, an internationally known architect, is leading the project.

The 14 stained-glass windows, each 22 feet tall, depict the seven days of creation and Jews' acceptance of religious laws. Parrendo, who died in 2016, created the windows in close consultation with Rabbi Herman Hailperin, who led the Tree of Life congregation for 40 years.

The windows were installed in the late 1960s in the main sanctuary, which was vacant during the Oct. 27, 2018, massacre. Eleven people died and six people, including four police officers, were injured during the worst antisemitic attack in America.

Stained-glass artists draw cartoons, which are blueprints of their design. For the restoration, the workers are using Parrendo's original drawings along with paper rubbings made for each window when they were removed in January. The work will take at least a year.

David Parrendo, who manages Hunt Stained Glass Studios, believes his late father's spirit is present in the South Side studio. "He's guiding us," he said.