Old St. Patrick's Church, also known as St. Patrick's Roman Catholic Church and commonly known as Old St. Pat's, is a Roman Catholic parish in Chicago, Illinois. Located at 700 West Adams Street, it has been described as the "cornerstone of Irish culture" in Chicago. The main church building is one of a handful of structures remaining in the city that predate the 1871 Great Chicago Fire, and is the city's oldest standing church building. Old St. Patrick's Church was founded on Easter Sunday, April 12, 1846.