Designed by the revered Edinburgh architect Robert Adam, right, it was the last section of the New Town to be built, between 1791 and 1820, although Adam died a year after work began.
It became home to landed gentry, law lords and distinguished military and medical men – among its residents were Lord Cockburn, Solicitor General for Scotland, celebrated conservationist, Elizabeth Grant of Rothiemurchus, author of Memoirs of a Highland Lady, and Baron Lister, pioneer of antiseptic surgery. Field Marshal Earl Haig was born at No 24.
As commerce expanded in the 20th century, the square's character changed, with financial and legal firms taking over the former homes as offices. In the computer age of the 1980s and 1990s, however, an exodus began to more modern offices.
The original raised pavements, allowing easy access to carriages have been retained and all the buildings overlook the central garden with its equestrian statue of the Prince Consort, Albert, unveiled by his widow Queen Victoria in 1876.
The square's garden, normally closed to the public, plays host to the Edinburgh International Book Festival every August.
Number 6, one of several properties still owned by the National Trust for Scotland, is Bute House, official residence of Scotland's First Minister.