St. Mary's Roman Catholic Church, also known as Old St. Mary's, is a historic church in Philadelphia, Pennsylvania. It is located in the Society Hill neighborhood at 248 S. Fourth Street between Spruce and Walnut Streets.

Society Hill is a historic neighborhood in Center City Philadelphia, Pennsylvania, United States, with a population of 6,215 as of the 2010 United States Census. Settled in the early 1680s, Society Hill is one of the oldest residential neighborhoods in Philadelphia. After urban decay developed between the late 19th and early 20th centuries, an urban renewal program began in the 1950s, restoring the area and its many historic buildings. Society Hill has since become one of the most expensive neighborhoods with the highest average income and second-highest real estate values in Philadelphia. Society Hill's historic colonial architecture, along with planning and restoration efforts, led the American Planning Association to designate it, in 2008, as one of the great American neighborhoods and a good example of sustainable urban living.