thumb|330px|right|View of Haymarket Square, an 1863 illustration
Haymarket Square is the historic name of a former town square in Boston, located between the North End, Government Center, the Bulfinch Triangle, and the West End. The square was a well-known feature of Boston from the mid-19th century to the mid-20th century, when the buildings around it were demolished to make way for the Central Artery and Government Center. The Haymarket produce market continues to operate at a location near the historic site of the square. The Haymarket MBTA station extends under the former site of the square.
17th and 18th centuries: Mill Cove to Mill Pond
thumb|1645 map
thumb|right|1743 map
During the early years of European settlement, the future site of Haymarket Square was in a part of Boston Harbor called Mill Cove.
The future location of Haymarket was just north of the "Water Mill" shown on the 1743 map.
19th century: creation of the square
Mill Pond was cut off from most water flows by the mill dam, and was used as a waste dumping site by neighboring homes and businesses. The polluted water was regarded as a source of disease.) permission to begin filling in the pond. A street plan for the filled land was proposed in 1808 by Charles Bulfinch.
Maps from as early as 1814 show a market at the intersection of Merrimack, Canal, and Charlestown Streets. No earlier map on the City of Boston atlas includes the name. A drawing published in 1895 entitled "View of the New Land in 1828" also shows the name "Haymarket Square". The name was applied because the square was "the site of one of several public scales used for weighing and selling hay." Images from the mid-1800s show hay being sold in the square. The Haymarket Pushcart Association, which traces its history to 1820, still operates the Haymarket market a block away.
From its opening in 1845 to its demolition in 1897, the most prominent building on the square was the Boston and Maine Railroad depot. According to an 1892 guidebook, "The Boston and Maine Railroad, alone of all lines entering the city on the north side, enjoys the privilege of penetrating within the outer street. Its station is in Haymarket Square, and the open space in front of it gives prominence to the structure." The railroad provided service to Lowell, Portland, and Lake Winnipesaukee. (a branch of Boston City Hospital) and the Canal Street incline (the northern end of the Tremont Street subway, the predecessor to the MBTA Green Line). The Haymarket station on the subway line opened in 1898, with an entrance kiosk in the center of Haymarket Square. Workers excavating for the station and incline uncovered a portion of the wall of the Middlesex Canal, which formerly terminated at the square.
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File:Manuscript plan of the Bulfinch Triangle, Boston, MA (2674588524).jpg|Plan for the filling of the Bulfinch Triangle, 1807. Haymarket Square is at bottom center, at the southern end of Canal Street.
File:Old Boston. Beacon Hill from Mt. Vernon St., near the head of Hancock St. - from a drawing made on the spot by J.R. Smith in 1811, 12 ; J.H. Bufford's Lith. 313 Washington St. LCCN2002725395.tif|"The Taking Down of Beacon Hill", by John Rubens Smith
File:Bulfinch Triangle detail of 1844 Boynton Plan of the City of Boston.JPG|1844 map with the first use of the name "Haymarket Square"
Image:View of the new land in 1828, Boston.JPG|"View of the new land in 1828"
Image:Boston and Maine Railroad terminal from stereo card.jpg|Boston and Maine depot
Image:Haymarket Square.JPG|1909 view. The kiosk is an entrance to the Haymarket station of the Tremont Street Subway. The Haymarket Relief Station is at rear.
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20th century: destruction
All the buildings around the square, as well as the square itself, were demolished in the 1950s for the construction of the elevated Central Artery During the construction of the 2,300-space Government Center Garage, the MBTA Haymarket Station was rebuilt. The northeast corner of the garage was located on the former location of Haymarket Square.
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Jack Frost--Connecting Links As Seen from Customs House Tower.jpg|1955 drawing by Jack Frost. Haymarket Square is in the center, with the new Central Artery at right.
Aerial view of Haymarket Square and North Station, 1960s.jpg| 1960s view to the north. The land at the left had been cleared for the construction of Government Center.
Construction of Federal Building, Government Center, Boston, 1960s.jpg|The JFK Federal Building under construction in the 1960s. Haymarket Square and the Haymarket Relief Station are at right.
Boston skyline 1960s, including Custom House Tower and State Street Bank Building.jpg|Late 1960s view from the north, with the elevated Central Artery at left. What remains of Haymarket Square is the traffic circle at the center.
Haymarket Square Boston, overlay of 2006 building footprints on 1881 Mitchell map.JPG|Approximate location of 2006 buildings overlaid on an 1881 map. No 1881 buildings remain.
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21st century: further changes
thumb|upright|[[Bulfinch Crossing under construction in 2022]]
Construction began in January 2017 on Bulfinch Crossing, a 2.9 million square foot redevelopment on the site of the Government Center Garage. The northeast corner of the garage is at the location of Haymarket Square.
"Haymarket Square" was the original name of a hotel and market building which began construction in 2018 on Blackstone Street, a block south of the historic location of Haymarket Square. The hotel's name was later changed to the "Canopy by Hilton Boston Downtown". The hotel opened in 2022.