Martin Place is a pedestrian mall in the Sydney central business district, New South Wales, Australia, which has been described as the "civic heart" of Sydney. As home to the Australian Securities Exchange, Reserve Bank of Australia, Commonwealth Bank, Macquarie Bank, Westpac, and other corporations, it is also a centre of finance and trade. Martin Place has been compared to other major financial districts such as Wall Street in New York City and the Square Mile in London. The General Post Office (GPO) is also located on Martin Place.

Martin Place has become a national Australian icon in popular culture for attracting high-end film and television productions and actors to the area. Martin Place runs between George Street and Macquarie Street, and provides entrances to the Martin Place railway station below street level. Other cross streets include Pitt Street, Castlereagh Street, Elizabeth Street and Phillip Street.

The initial "Martin Place" was the section between George Street and Pitt Street, officially opened 1892, and was named in honour of Sir James Martin, the three time Premier of New South Wales and Chief Justice of Supreme Court of New South Wales. Closed to traffic in stages from 1971, Martin Place is surrounded by many heritage buildings and features the 1927 World War I Sydney Cenotaph, water fountain, entertainment area, railway access and pedestrian seating.

Today's Martin Place was built in several phases. Until the late 19th century, only the section between Pitt Street and Castlereagh Street existed in anything resembling the present form, as a short street named Moore Street. Between Pitt Street and George Street there was only a small laneway (similar to nearby surviving laneways such as Angel Place or Hosking Place). In 1863, construction began on the present General Post Office Building on the south side of the laneway. The building was constructed in stages, and when the design changed to provide for a main façade on the longer north side (instead of facing George Street to the west), there were concomitant proposals to widen the existing laneway into a street connected to Moore Street. A fire which destroyed properties to the north of the laneway provided the impetus for the construction, and in 1892 (a year after the Venetian-Italianate-style General Post Office was completed) the widened street was officially opened and named "Martin Place", in honour of New South Wales premier and Chief Justice James Martin. The General Post Office occupied the entire southern frontage of the street.

Both Moore Street and Martin Place became prominent centres of business and finance in Sydney. In 1913, the headquarters of the Commonwealth Bank was constructed on the corner of Moore Street and Pitt Street. In later years, other banks followed with a range of impressive buildings (see "Architecture" below). In 1921, Moore Street was renamed as part of Martin Place.

Conscription rallies for World War I took place here. In 1927, a Cenotaph commemorating the WWI dead was erected. Soon after, the Sydney Municipal Council proposed to extend the street further east towards Macquarie Street. However, the plan was delayed by concerted opposition from landowners of the buildings that would have to be demolished to make way for the extension. One of the buildings demolished to make way for the extended Martin Place was St Stephen's Presbyterian Church, on the east side of Phillip Street, which was replaced by the present church on Macquarie Street in 1935. The extension was finally completed in 1935, resulting in the Martin Place stretching from George Street to Macquarie Street seen today.

A number of the street's older buildings were demolished to make way for new buildings in the mid 20th Century. The most prominent of these was The Australia Hotel demolished in 1971, and replaced by the commercial office tower and retail development MLC Centre in 1977 (now known as 25 Martin Place) designed by architect Harry Seidler. In 1982 the art deco Rural Bank Building was demolished to make way for the post modern State Bank of NSW, completed in 1986.

The increasingly important role of Martin Place as the 'heart' or 'town square' of Sydney (see "Events" below) led to calls for the street to be pedestrianised. This was undertaken progressively from 1971 until 1979, when the whole street became a pedestrian mall. During this period three properties, the ANZ bank, the National Mutual building, and the CML building, were saved from destruction after the NSW Builders Labourers Federation placed green bans to enforce National Trust preservation orders. The closure of the street to traffic was partly timed to coincide with the construction of Martin Place railway station under the eastern section of the street. Martin Place was closed between Macquarie and Phillip Streets from January 1972 to facilitate the station's construction. The station opened in 1979. Leo Port, the Lord Mayor of Sydney was an advocate of civic design, and was partly responsible for the pedestrianisation of Martin Place and Sydney Square.