The current building standing at 45 School Street was built over a period of three years in the 1860s. It was notable in its day for its architecture, what is now known as the Second Empire Style, popularized by the Louvre, in Paris, but introduced in the US by Gridley J. Fox Bryant in his design of Old City Hall (he would go on to design the Transcript Building in the same style, as well as the State House). His building was not the first to occupy the site, however; it had previously held the Boston Latin School, which Benjamin Franklin briefly attended, and the Suffolk County Courthouse, which was converted into the original city hall before its demolition in 1862. Granite blocks from the courthouse were used in the construction of the rear and east walls of Old City Hall. A time capsule was imbedded in the southeast cornerstone, containing a silver plate engraved with the names of those involved in the building process, a message from the President to Congress in 1862, reports from several branches of government, and the 1862 Massachusetts Register. Other features of the building include murals depicting the history of the site and a statue of Benjamin Franklin that is considered the first portrait statue in Boston.

Old City Hall was the inspiration for the setting of Edwin O’Connor’s 1956 novel The Last Hurrah. The book chronicles the final mayoral campaign of the politician Frank Skeffington in an unnamed East Coast city, which is believed to be Boston. At seventy-two years old, Skeffington’s bid for another term is a “last hurrah” for classical, old school urban politics. Critics believe that his character is based on James Michael Curley, who served terms as the 41st, 43rd, 45th, and 48th Mayor of Boston in Old City Hall. Curley lost his final campaign at the age of seventy-five to city clerk John Hynes. This is believed to be the origin of the term “last hurrah.”

In 1969, City Hall was moved to its current location in Government Center. Old City Hall has been repurposed, but still receives over 500,000 visitors a year.