St. Peter's Church, also known as St. Peter's Pro-Cathedral, was a historic church in Baltimore, Maryland that served as the first Catholic pro-cathedral in the United States; first built in 1770, the church became the pro-cathedral of the Diocese of Baltimore when the diocese was created in 1789,[1] and the seat of Archbishop John Carroll, the first Catholic bishop in the United States.

[1] The trustees of the pro-cathedral purchased six acres of land in Baltimore in 1814 to use as a burial ground for Catholics of the city.

[4] It served as the pro-cathedral of the Archdiocese of Baltimore until an official cathedral, the Basilica of the National Shrine of the Assumption of the Blessed Virgin Mary, was built in 1821 to alleviate overcrowding at St.

[5][6] With an increase of the Catholic population of Baltimore from 800 in 1792 to 10,000, the pro-cathedral was only able to accommodate a tenth of its total parishioners at any given Sunday Mass.

St. Peter's was closed in 1841,[1] and demolished by 1845, when the Institute of the Brothers of the Christian Schools established Calvert Hall on the site.