Charterhouse Square is a historic square in Smithfield, London, United Kingdom. It lies between Charterhouse Street and Clerkenwell Road, in the extreme south of the London Borough of Islington, just north of the City of London.
In 1371 a Carthusian monastery was founded by Walter de Manny on what is now the north side of the square. It was established near a 1348 plague pit, which formed the largest mass grave in London during the Black Death, and tens of thousands of bodies were buried there. The name of the monastery, Charterhouse, was derived as an Anglicisation of La Grande Chartreuse, whose order founded the monastery.
The Charterhouse was dissolved as a monastery in 1537, and in 1545 was purchased by Sir Edward (later Lord) North (c. 1496-1564) and transformed into a mansion house. Following North's death, the property was bought by Thomas Howard, 4th Duke of Norfolk, who was imprisoned there in 1570 after scheming to marry Mary, Queen of Scots. Later, Thomas Sutton bought the Charterhouse, and on his death in 1611, endowed a hospital (almshouse) and school on the site, which opened in 1614, supporting 80 pensioners (known as 'brothers'). The school for boys coexisted with the home for pensioners until 1872 when Charterhouse School moved to Godalming in Surrey. Following this, the Merchant Taylors' School occupied the buildings until 1933. The square also lends its name to a preparatory school which occupies a building overlooking the square.
In July 2011, English Heritage granted Grade II listed status to the "setted" road surface in the Square, which was laid down in the 1860s.
 Current use
The Charterhouse Square campus of Queen Mary, University of London is situated on the north-east of the Square, occupying the former school lands. The campus includes student accommodation and departments of Barts and The London School of Medicine and Dentistry. The City of London Migraine Clinic is situated to the South-west of the Square.
Florin Court, a residential building in the Art Deco style built in 1936 by Guy Morgan and Partners, is located on the eastern side of the square. The building has a curved facade, roof garden and basement swimming pool.
The nearest underground station to the Square is Barbican to the south-east. The barbican bus stop is also near by.
 In fiction
- Palmer, Jason (March 15, 2013). "'Black Death pit' unearthed by Crossrail project". Retrieved March 15, 2013.
- Charterhouse history accessed 19 Jun 2007
- "English Heritage grant protection to three Islington landmarks". Islington Tribune. 22 July 2011. Retrieved 10 January 2012.
- Art Deco London accessed 19 Jun 2007
- Agatha Christie's Poirot (1989-) Screen online accessed 19 Jun 2007
- LondonTown.com information
- The Charterhouse Square School website
- Charterhouse Square campus at Queen Mary, University of London
- The City of London Migraine Clinic website