St. Paul's Cathedral is located at 472 Richmond Street, on the east side of Richmond Street between Queens Avenue to the south and Dufferin Avenue to the north, in the downtown area of the City of London. The two storey red brick building and tower were constructed in 1846. A painted red brick addition was constructed between 1894 and 1895. There are twelve grave markers and a cast iron fence also visible.

The property was designated, by the City of London, in 2005, for its historical and contextual value or interest, under Part IV of the Ontario Heritage Act (By-law L.S.P. – 3373-297).

The open space surrounding St. Paul's Cathedral accentuates the Cathedral from the surrounding buildings. The grounds of the Cathedral once served as a graveyard for the village of London. Most of the interred and their grave markers were transferred to Woodland Cemetery, which is owned and operated by the Cathedral. Twelve marked graves remain on the Cathedral grounds as reminders of London's early pioneer days.

The Cathedral is enclosed with a unique cast-iron beaver-motif fence, reflecting the Diocese of Huron's coat of arms. The original portion was purchased by the Cathedral in 1887 to demarcate the property along Richmond Street. In 1974, additional fencing was added, to surround the entire property.

St. Paul's Cathedral, the oldest church in London and the seat of the Diocese of Huron, opened for worship on Ash Wednesday in 1846. The first frame church was destroyed by fire on Ash Wednesday in 1844. Between 1894 and 1895, the Cathedral was enlarged with a small tower and included Cronyn Hall which was dedicated to the first Bishop of the Diocese of Huron, Reverend Benjamin Cronyn. Cronyn Hall was built to house the church and synod offices, and to provide a hall for meetings. The Cathedral has been used continuously as a place of worship for over 150 years and is also notable for having housed the first election of an Anglican Bishop in Canada, in 1857.

The Cathedral is one of the most magnificent churches in the City of London and its many notable architects, builders and contributors enhance this status. The nave and tower, built of yellow brick, later painted red, to match the Cronyn Hall addition, are fine examples of the English Gothic Revival style and they were designed by William Thomas. Thomas was a distinguished architect from Toronto who designed many exemplary buildings, including St. Michael's Cathedral in Toronto and Brock's Monument at Queenston. Mr. Spier and Mr. Rohns of Detroit, Michigan, designed the later chancel and transepts under the supervision of local architect, John. M. Moore. The pinnacles on many parts of the building and the main doorways feature gargoyles carved from stone which was quarried at Portland Bill. This was the same stone that Sir Christopher Wren used to build St. Paul's Cathedral in London, England. Also of note are the wide transepts and spacious chancel. The dominating main tower features the original six peal of bells cast by Mears Company of London, England in 1851. The bells were shipped across the Atlantic Ocean and then conveyed from Port Stanley to London by oxcart. In 1901, the clock and chime of 10 bells, made by Gillett and Johnston of England, were donated by the Meredith family.

The stained glass windows of St. Paul's Cathedral are of finest quality and design and are one of the most outstanding aspects of the Cathedral. The windows of most significance were created by the Louis Tiffany Company in the late 19th century, including the two windows next to and opposite the Nativity window. During the 150th anniversary of the Cathedral, four new stained glass windows, designed and made by Christopher Wallis, were placed in the remaining locations in the nave. Three of the windows depict the life of St. Paul and the fourth is a Nativity window.