James Renwick Jr. (1818-1895) was an American architect known for his significant contributions to the Gothic Revival style in the United States. He designed several notable buildings, including the Grace Church in New York City and the Smithsonian Institution's Castle in Washington, D.C. His work is characterized by intricate detailing and a strong sense of verticality. Renwick was also involved in the design of various educational and religious structures, showcasing his versatility as an architect. His influence extended beyond his lifetime, as many of his designs continue to be celebrated for their artistic and historical value.