From the Parish website at: http://oldstmarys.com/

Originally known as Saint Mary of the Assumption, our present parish began its story in April 1833, when the “Catholics of Chicago” signed and sent a petition to Bishop Rosati of St. Louis which said in part:

“We, the Catholics of Chicago, Cook County, Illinois, lay before you the necessity there exists to have a pastor in the new and flourishing city. We count about 100 Catholics in this town. We will not cease to pray until you have taken our important request into consideration.”

The original Saint Mary’s Church was built in 1833 on the south side of Lake Street, west of State Street. The building was moved to the northwest corner of Michigan at Madison in 1836 where it was enlarged and an open belfry added. In 1843, with the establishment of the Diocese of Chicago, St. Mary’s Cathedral was built on the southwest corner of Madison at Wabash. The original wooden structure was cut in half and moved to the grounds of the cathedral where the first Catholic grammar school in Chicago was established in 1846. When the Cathedral was destroyed in The Great Fire in 1871 and plans were made for a new cathedral parish (Holy Name) north of the Chicago River, the Plymouth Congregational Church at 9th and Wabash (which had survived the fire) was purchased and became known as Old St. Mary’s.