In a city as old as Edinburgh, one question which arises with relative regularity is which building, precisely, is the city's oldest? Luckily for us, there is a specific answer to that!

Found within the complex of buildings that make up Edinburgh Castle, St Margaret's Chapel is considered to be the oldest surviving building in the city which still retains something of its original function.

​Many churches in particular have been repurposed over the years, and St Margaret's Chapel hasn't always served as a site of religious worship, but the building today still offers the same experience that it was built to provide nearly 900 years ago.

It may not seem especially interesting from the outside, but this small but perfectly formed structure has survived fire, war, revolution, Reformation, military occupation and a rapid rise in tourism over the last couple of decades - and still it stands!

The building was built originally on the instruction of David I of Scotland, who was also responsible for establishing Holyrood Abbey at the eastern end of the medieval city. It is approximately 15 feet (4.5m) wide by about 30 feet (9m) long and is built right at the summit of the castle rock, at the highest point of the castle - what must have been considered an estimable location for communing with God! ​

Over its history there have been various additions, restorations and improvements to the chapel structure, but the earliest part of its construction is considered to date back to around the late 1120s. Queen Margaret had been married to Malcolm III (known as 'Canmore' or 'Bighead') and died at Edinburgh castle in 1093.

​She had previously established the ferry service over the waters of the Firth of Forth, to the north of Edinburgh, for the central purpose of improving access to St Andrews for religious pilgrims, and the two towns established on the banks of the water where the crossing was made are still named North Queensferry and South Queensferry. In 1250 Margaret was canonised, and having been Queen Margaret of Scotland became St Margaret of Scotland.

Hence the chapel that David originally created in honour of his mother would have been Queen Margaret's Chapel, only a century or more later becoming dedicated to her as saint.

In 1314, during Robert the Bruce's 'scorched earth' policy of removing all fortresses and structures which might have been used by the English army as places of shelter or embattlement, he ordered all the buildings of Edinburgh Castle to be demolished, with the exception of St Margaret's Chapel. Later, on his deathbed in 1329, Bruce ordered the restoration of the chapel, with a provision of 40 Scots pounds being set aside for this purpose.

One notable occupant of the chapel, in the sixteenth century, was Mary of Guise, the mother of Mary, Queen of Scots. While Mary was overseas in France, her mother remained in Scotland, and stayed at Edinburgh Castle to hold the fortress on her daughter's behalf. In May 1560, after several months of declining health, Mary died. Her body was embalmed and laid in a lead coffin inside St Margaret's Chapel for several months (partly due to the English holding the port of Leith under siege) until she could finally be transported to France for burial in March 1561. 

The University of Edinburgh has campus buildings across the Old Town and beyond, designed by a whole host of notable architects who have left the imprint of their style and vision on the city. And the university's first dedicated campus building to be built was Old College, which remains an iconic structure in the heart of the city. 

Although the university was founded by James VI in the sixteenth century, Old College was built just over two hundred later, intended as a visible symbol of the university's status as a centre of academia and learning at the tail end of the period known as the Scottish Enlightenment. Land was secured adjacent to South Bridge (thanks in part to the political manoeuvring of Henry Dundas) and the plans for the building were drawn up by Robert Adam, who had also given the New Town its high status stylings, as seen on Charlotte Square (and, indeed, South Bridge itself).

The land on which the college was built originally lay partly beyond the city boundary itself, and had previously been occupied by a medieval church and hospital called St Mary-in-the-Fields (ie. not in-the-city), commonly known as Kirk o'Field, adjacent to which was the house in which Henry Darnley, the second husband of Mary, Queen of Scots, was staying on the night of his murder in 1567. It can only be a coincidence that the university, established by James VI, had its first custom-built college space on the same site where his father had died...

Robert Adam drew up the plans for Old College, which had only been partly constructed when Adam died in 1792. Funding for the college project ran short, and the building work stopped until early twenty years later. At that time, Adam's uncompleted plans were passed to another architect, William Henry Playfair, who made modifications to the project in order to get the work completed, and the building - called New College - was finished in 1827. 

Playfair's changes to the design of the college had been intended to reduce the cost. Whereas Adam had intended the building to form two square quadrangles - a kind of figre-of-eight shape - Playfair took out the central range of the buidling to leave a single rectangle of space at the heart of the building. He also removed the ostentatious dome which Adam had planned for the east entrance to the building, and imposed his style on the internal spaces of the college.

Although Old College remains actively used by the University of Edinburgh, housing their law school along with various academic office functions, there is a publicly accessible area which shows Playfair's classical internal space, which is the Talbot Rice gallery. This free-entry art gallery is worth visiting to see Old College from the inside.

Sixty years after Playfair's vision for New/Old College was complete, the university had sufficient funds to be able to reinstate the kind of grand dome that Robert Adam had intended for the building. Designed by Sir Robert Rowand Anderson, who had also built the nearby McEwan Hall for the university's students to graduate in. The stonework of the dome is noticably differen in colour and texture even today, indicating that it was added to the building later than the bulk of the construction. 

Anderson's dome was topped by the figure which makes the Old College dome most easily recognised on Edinburgh's skyline today: popularly known as the Golden Boy, sculpted by John Hutchison, the statue represents the figure of Youth holding the torch of Enlightenment - the two principles for which the university was founded. 

Students who attended classes in Old College included Charles Darwin, in the 1820s, and Sir Arthur Conan Doyle in the 1870s.

In 1923, the Robert Lorimer-designed memorial to university figures who lost their lives in the First World War (with similar losses from World War Two added later) was installed, creating a public memorial at the west end of the central quadrangle which today forms a patch of grass on which students can be found relaxing during the early summer months. 

In the middle of the nineteenth century the University of Edinburgh commissioned William Playfair to design a new purpose-built college space, which was built at the top of the Mound - this building took on the mantle of New College, and the building which had once been New College became​ Old College.