By 1876, with the completion of the Museum of Fine Arts, Walter Muir Whitehill noted that "Copley Square which — unlike the rest of the Back Bay — had never been properly or reasonably laid out, was beginning to stumble into shape". But the land comprising the current square, bisected diagonally by Huntington Avenue, was still available for commercial development. The city purchased the larger triangle, then known as Art Square, in 1883 and dubbed it Copley Square. The smaller plot, known as Trinity Triangle, was the subject of several lawsuits against the property owner, who planned to put up a six-story apartment building directly in front of Trinity Church. Foundations were laid but further construction was delayed by various injunctions. The city council appropriated funds for purchase of the triangle in 1885. Calls to close off Huntington between Dartmouth and Boylston streets began almost immediately, but that was not accomplished until 1968.

In 1966, a proposal by the Watertown, Massachusetts, landscape design firm Sasaki, Dawson, DeMay was selected from 188 entrants in a national competition sponsored by the city and private development concerns. The design centered on a sunken terraced plaza, intended to separate the pedestrian from the noise and bustle of the surrounding streets, but it also isolated the square from the community. As the architecture critic Robert Campbell noted, "From the day it opened, it didn't work".

In 1983 the Copley Square Centennial Committee, consisting of representatives of business, civic and residential interests, was formed. They announced a new design competition, funded by a grant of $100,000 from the National Endowment for the Arts. The winner, announced in May 1984, was Dean Abbott of the New York firm Clarke & Rapuano. The park was raised to street-level and a lawn and planting beds were added. The fountain, which had rarely functioned as intended, was re-configured. The updated park was dedicated on June 18, 1989, and received mixed reviews.

By 2021 the park, now heavily used, was again in need of redesign; requirements included alleviating stress on existing trees, adding more trees, making the fountain safer, and prioritizing ease of maintenance. After a series of public meetings, the final proposal by Sasaki Associates was presented to the city in May 2022. Renovations began on July 20, 2023, and are expected to take sixteen months.

The non-profit membership organization Friends of Copley Square was formed in 1992 as a successor to the Copley Square Centennial Committee. It raises funds for care of the square's plantings, fountain, and monuments, and also manages the Copley Square Charitable trust.

The Boston Marathon foot race has finished at Copley Square since 1986. A memorial celebrating the race's 100th running in 1996 is located in the park, near the corner of Boylston and Dartmouth streets.

• 1874 A surveyor's map shows a "Chemical School, Inst. Tech." (never built) and four house lots on the larger triangle.
• 1894 A circular, sunken garden combining designs by Rotch & Tilden and Walker and Kimball, ringed with trees and marble balustrades, centered on a small fountain.
• 1912 A plan by architect Frank Bourne eliminated the Huntington Avenue crossing and sunk the square 2.5 feet below street level. One version featured an enormous monumental column in the center of the plaza.
• 1914 Landscape architect Arthur Shurtleff envisioned a circle of trees around the Brewer Fountain, which would be moved from Boston Common.
• 1927 A proposal for a State War Memorial, from plans by Guy Lowell, placed a large, cylindrical granite structure in a basin. The inner chamber rose fifty feet to a domed ceiling and the memorial was topped with bronze representation of Hope.
• 2012 A juried competition held by SHIFTBoston invited designs for creative illumination. First prize was awarded to the firm Khoury Levit Fong for their conceptual chandelier of LEDs suspended over the square.

On April 15, 2013, around 2:50 pm (about three hours after the first runners crossed the line) two bombs exploded‍—‌one near the finish line near the Boston Public Library, the other some seconds later and one block west. Three people were killed and at least 183 injured, at least 14 of whom lost limbs.

Copley is served by several forms of public transportation:

• Copley Station on the MBTA Green Line
• Several MBTA bus routes; the square is a major transfer point and terminal for several local and express routes
• Logan Express to Logan International Airport
• Nearby Back Bay station for MBTA Orange Line, MBTA Commuter Rail, and Amtrak

Major roads:

• Massachusetts Turnpike
• Boylston Street

• Pokorny, Margaret, ed. (October 23, 2002). Copley Square: The Story of Boston's Art Square (PDF). Boston: Friends of Copley Square. Archived from the original (PDF) on May 28, 2013. Retrieved June 6, 2022.
• Shand-Tucci, Douglass (1999). Built in Boston: City and Suburb 1800–2000. Foreword by Walter Muir Whitehill (Revised and Expanded ed.). Amherst: University of Massachusetts Press. ISBN 1-55849-201-1. LCCN 99016750. Retrieved June 11, 2022.
• Whitehill, Walter Muir (1968). Boston: A Topographical History (Second, enlarged ed.). Cambridge, Massachusetts: The Belknap Press of Harvard University Press. ISBN 0-674-07951-5. Retrieved June 11, 2022.

• Aldrich, Megan (1994). Gothic Revival. London: Phaidon Press. ISBN 978-0-7148-2886-2.
• Bunting, Bainbridge (1967). Houses of Boston's Back Bay: An Architectural History, 1840-1917. Cambridge: Belknap Press, an imprint of Harvard University Press. ISBN 978-0-674-40901-9.
• Forbes, Esther (1947). The Boston Book. Photographs by Arthur Griffin. Boston: Houghton Mifflin. OCLC 851279970.
• Kay, Jane Holtz (1999). Lost Boston (Expanded and updated ed.). Boston: Houghton Mifflin. ISBN 978-0-395-96610-5.
• Shand-Tucci, Douglass. "The Gods of Copley Square: Dawn of the Modern American Experience, 1865-1915", www.backbayhistorical.org/Blog, 2009. All chapters archived at Open Letters Monthly.
• Shand-Tucci, Douglass. "Renaissance Rome and Emersonian Boston: Michelangelo and Sargent, between Triumph and Doubt", Anglican Theological Review, Fall 2002, 995–1008.
• "Greetings from Copley Square: A Chronology in Postcards", Exhibitions, Boston Public Library, 2010, archived from the original on July 23, 2014

Wikimedia Commons has media related to:
Copley Square (category)

• Copley Square Farmers' Market
• Friends of Copley Square
• Boston Public Library Copley Square Collection – via archive.org
• Boston Streetcars: Copley Square A history of public transportation around and through Copley Square
• View of Copley Square, 1974 Photograph by Nicholas Nixon of the first iteration of the plaza with the John Hancock tower in its "plywood palace" phase.
• Copley Connect pilot project Held in June 2022, the city closed one block of Dartmouth street to create a plaza. "For the first time in its history, Copley Square was unified as a grand civic space, bookended by Boston Public Library's McKim Building and H.H. Richardson's Trinity Church."

42°21′00″N 71°04′34″W / 42.350°N 71.076°W / 42.350; -71.076 (Copley Square, Boston)