St Bartholomew's Hospital, also known as Barts, is a teaching hospital located in the City of London. It was founded in 1123 by Rahere, and is currently run by Barts Health NHS Trust.

Barts was founded in 1123 by Rahere (died 1144, and entombed in the nearby Priory Church of St Bartholomew the Great), a favourite courtier of King Henry I. The dissolution of the monasteries did not affect the running of Barts as a hospital, but left it in a precarious position by removing its income. It was refounded by Henry VIII in December 1546, on the signing of an agreement granting the hospital to the Corporation of London.

The hospital became legally styled as the "House of the Poore in Farringdon in the suburbs of the City of London of Henry VIII's Foundation", although the title was never used by the general public. The first superintendent of the hospital was Thomas Vicary, sergeant-surgeon to King Henry, and an early writer on anatomy. It was here that William Harvey conducted his research on the circulatory system in the 17th century, Percivall Pott and John Abernethy developed important principles of modern surgery in the 18th century, and Mrs Bedford Fenwick worked to advance the nursing profession in the late 19th century.

From 1839 to 1872, the mortality reports show that surgical trauma and postoperative infection were the greatest causes of death. Tuberculosis, however, remained the most fatal nontraumatic cause of death. Nurses were expected to work 12 hours a day, and sometimes 14, with meal breaks in 1890. They had 2 weeks annual holiday. Upon the creation of the National Health Service in 1948, it officially became known as St Bartholomew's Hospital.

Barts is the oldest hospital in Britain still providing medical services which occupies the site it was originally built on, and has an important current role as well as a long history and architecturally important buildings. The Henry VIII entrance to the hospital continues to be the main public entrance and features a statue of Henry VIII above the gate.

Its main square was designed by James Gibbs in the 1730s. Of the four original blocks, three survived; they include the block containing the Great Hall and two flanking blocks that contained wards. The first wing to be built was the North Wing, in 1732, which includes the Great Hall and the canvas paintings by William Hogarth. The South Wing followed in 1740, the West in 1752 and finally the East Wing in 1769. In 1859, a fountain was placed at the square's centre with a small garden.

St Bartholomew's Hospital has existed on the same site since its founding in the 12th century, surviving both the Great Fire of London and the Blitz. Its museum shows how medical care has developed over this time and explains the history of the hospital. Part-way around the exhibition is a door which opens on to the hospital's official entrance hall. On the walls of the staircase are two canvases painted by William Hogarth, The Pool of Bethesda (1736) and The Good Samaritan (1737). Hogarth was so outraged by the news that the hospital was commissioning art from Italian painters that he insisted on painting the canvases without a fee, as a demonstration that English painting was equal to the task. The Pool of Bethesda is of particular medical interest, as it depicts a scene in which Christ cures the sick: display material on the first floor speculates in modern medical terms about the ailments from which Christ's patients in the painting are suffering. The canvases were restored in the early 2020s, with a grant from the National Lottery Heritage Fund, and opened for public viewing in early Autumn 2025.

The room to which the staircase leads is the hospital's Great Hall, a double-height room in Baroque style. Although there are a few paintings inside the Great Hall, nearly all are on movable stands: the walls themselves are mostly given over to the display of the very many large, painted plaques which list, in detail, the sums of money given to the hospital by its benefactors.