[1] It was developed in 1777 on the site of a previous area of green space to the north of the City of London known as Finsbury Fields, in the parish of St Luke's and near Moorfields.
Past residents of the square include Pascoe Grenfell Hill, Thomas Southwood Smith and Philip Henry Pye-Smith.
[5] The site is now occupied by City Gate House which was designed by Frederick Gould and Giles Gilbert Scott and completed in 1930.
[6] In 1784, Vincenzo Lunardi achieved the first successful hot air balloon flight in England from the adjacent Artillery Ground.
The oldest (westernmost) section (with its cupola and clock on the corner with City Road) dates from 1904 to 1905 and was built by John Belcher as headquarters for the Royal London Friendly Society; over the next ten years this building was extended eastwards by four bays.
The adjacent, taller section, with its prominent tower-cum-spire, dates from 1929 to 1930; it was built by Belcher's former partner, J. J. Joass, to form an expanded headquarters for the Royal London Mutual Assurance Society.
[2] In the 1980s, the older (pre-1940s) buildings were all comprehensively redeveloped, by Sheppard Robson & Partners, to form a new office complex: Triton Court.
The interiors were gutted and rebuilt, but the façades were retained, albeit with the addition of a double-height mansard roof and the insertion of a new entrance arch through the four-bay extension to the original Edwardian block.