Saint Patrick's Cathedral, New York City, largest Roman Catholic church in the United States. The Gothic building at Fifth Ave. between 50th and 51st St. replaces an earlier cathedral at Mott St. The original plans, by James Renwick, were executed in 1853; the cornerstone was laid in 1858; in 1879 the building was dedicated. The Lady Chapel behind the high altar was added later, using the plans of Charles T. Matthews. The cathedral is of marble in the traditional cruciform shape and has 12 side chapels, many stained-glass windows, and a chime of 19 bells.