Sts. Constantine and Helen Greek Orthodox Cathedral

The Greek Orthodox Cathedral of Sts. Constantine and Helen, more simply Sts. Constantine and Helen Cathedral is a Greek Orthodox cathedral church at 64 Schermerhorn Street in Downtown Brooklyn, New York. It is best known for taking in parishioners from St. Nicholas Greek Orthodox Church in Manhattan, destroyed during the September 11 attacks.

Founded in 1913, it was the first Greek Orthodox parish on Long Island, and is one of the oldest Greek Orthodox churches in the City of New York. After meeting for several years in a small building at Johnson and Lawrence streets, the community raised funds to build a new structure, whose cornerstone was laid April 16, 1916.