Its original medieval buildings from the 1382 foundation remain largely intact, but they have been supplemented by multiple episodes of construction.
There was a major expansion of boarding accommodation in the Victorian era; further teaching areas were constructed at the turn of the 20th century and more recently.
Among the styles in the architecture of the college are Perpendicular Gothic, Christopher Wren, Brunelleschi, Queen Anne revival, and High Victorian Baronial.
The foundation buildings are situated just south of Winchester's Cathedral Close and bordering a branch of the River Itchen.
The school is set in extensive grounds to the south, including the Meads playing fields, water meadows by the river, and St Catherine's Hill to the southeast.
Outer Gate has a handsome star-shaped lierne vault, described by the architectural historian Nikolaus Pevsner as "out-of-the-ordinary", such decoration usually being confined to churches.
[10] Outer Court is mainly medieval, but the east side is formed by the architect G. S. Repton's 1832–1833 reworking of the Warden's Lodgings in knapped flint laid in regular courses.
It retains its original wooden fan-vaulted ceiling, designed by Hugh Herland, carpenter to Richard II.
[10] In the early modern period, the College Sick House was built by the school's warden (chairman of governors) John Harris in 1656–1657.
[10] The school was greatly extended in the 19th century during Queen Victoria's reign, with the addition of boarding houses for "commoners", paying pupils, as opposed to the scholars who continued to live in the medieval College.
[21] The "forbidding" neo-Gothic Headmaster's House (no longer used for that purpose), its front in knapped and squared flint, the back in Georgian-style red brick, was built by the English architect G. S. Repton in 1839–1842.
[13] Flint Court, providing many of the school's classrooms and the teachers' common room, is open at the front; the wings to left and right are of 3 storeys, in red brick, described by Pevsner as "partly chequer, partly diaper"; the centre has a single-storey Perpendicular-style cloister in front of the full-height range.
[13] In the 1880s, a large Sanatorium, designed by the English architect William White, was built in High Victorian Baronial style in 1884–1893; it has been described as "an all too prominent feature"[22] of the school's landscape.
"[26] It was extended in the 21st century with a mixture of yellow brick, limestone dressings, glass, and zinc cladding.
[13] The Science School was designed by the English architect Henry L. G. Hill, who served as the college archivist.
It is in what the college calls Queen Anne revival style, and was completed in 1904; it remains in use for its original purpose.
[28] The separate Biology Block behind the Science School was added by the architect and college bursar[30] Ruthven O.
It was designed by Herbert Baker, architect of many colonial buildings in South Africa and New Delhi, and dedicated in 1924.
[31] A bronze bust of Old Boy Air Chief Marshal Lord Dowding sits on the west side of the cloister.
[31] The College's South Africa Gate on Kingsgate Street commemorates the Wykehamist dead of the 1899–1902 Boer War.
[20] Pevsner comments that the architect, Peter Shepheard, "lost his nerve" and chose to be "above all tactful" rather than making the hall modern; he calls the resulting exterior in "blue" brick with stone facings "not self-effacing ... [but] very noticeable, only in a pleadingly inoffensive way.
"[34] The development of a "Southern Campus" comprising a PE centre, swimming pool, rifle range, and squash courts by the architects Design Engine began in 2017 on the site between the Kingsgate Park sports field and the Norman Road tennis courts.