How an amateur Scots architect designed Capitol building where Donald Trump will be sworn in as US president

Now, in a grand building where memories of that dark day remain strong, Mr Trump will set foot in the US Capitol to be sworn in as the 47th president.

For aficionados of American politics, the stark contrast between the two events will be clear to see. Immediately after his official inauguration, Mr Trump is expected to decamp to the president’s room, an ornate space within the Capitol complex, to begin signing a slew of executive orders; the same ceremonial room was used by Chief Justice John Roberts during Mr Trump’s first impeachment trial.

But for US political geeks on this side of the Atlantic, the decision to hold the inauguration inside the Capitol building itself due to the freezing temperatures in Washington DC is of extra significance.

The historic building, the seat of the US Congress, was designed by William Thornton, a Scottish architect and polymath. His name and legacy is little known nowadays, and even during his lifetime, Thornton was an unlikely architect of one of the world’s most recognisable structures.

At the time, it was widely expected the French engineer, Pierre Charles L'Enfant, who was hired by George Washington to plan the new city of Washington on the banks of the Potomac river, would oversee the construction of the Capitol itself. But he failed to produce any drawings or designs, and every other design that was submitted as part of a 1792 competition arranged by then secretary of state Thomas Jefferson was deemed substandard.

In October that year, long after the contest had closed, Thornton sent a letter to the commissioners tasked with laying out the new city and its cluster of government buildings. “I have made my drawings with the greatest accuracy, and the most minute attention,” he told them. “In an affair of so much consequence to the dignity of the United States,” he added, it was his hope “you will not be hasty in deciding”.

Thornton’s vision of a Georgian mansion with a domed rotunda, fronted by a Corinthian portico, won over Jefferson and more importantly, Washington, who praised its “grandeur, simplicity and beauty”. His winning design was all the more remarkable considering Thornton was not a trained architect, having studied medicine at Edinburgh and Aberdeen universities. However, his notebooks showed how, even at a young age, he was nurturing a love of design and the arts, with the architecture of Edinburgh, especially that of the New Town, exerting a strong influence.

He would later write a friend of how he envisioned the Capitol as a building that embodied the spirit of the new American republic, stressing the importance of its “dignity of appearance”, and how “minutiae gave way to a grand outline, full of broad prominent lights and broad deep shadows”.

Thornton added: “I sought for all the variety of architecture that could be embraced in the forms I had lain down. I attended to the minute parts; that we might not be deemed deficient in those touches which a painter would require in the finishing.”

Thornton was raised in Tortola in the British Virgin Islands where his family part-owned a plantation and had around 70 slaves - a fact that troubled the Scot. But he was sufficiently intrigued by the burgeoning American experiment to emigrate in 1786.

Arriving in Philadelphia, he hoped to help free blacks to make their way to Sierra Leone, and became involved in the creation of an experimental steam ship. But frustrated by a lack of success, he returned to Tortola to pursue his interest in botany. By the time he began working on the Capitol design, he had earned his stripes as “a product of the Scottish Enlightenment”.

After his work on the Capitol, Thornton moved to Washington in 1794, and President Washington appointed him one of the city's commissioners. In 1802, President Jefferson appointed him head of the US patent office, an office Thornton held until his death in 1828.

Over the years, the expansion of the Capitol complex - most notably, the creation of the South Wing and the addition of the portico - have overshadowed Thornton’s initial designs. But in recent years he has received international recognition for his seminal work.

In 2019, the-then first minister Nicola Sturgeon referenced Thornton’s role in the Capitol’s design during a visit to the US. That same year historians and academics from the US and Scotland also gathered in the Capitol to pay tribute to the “true polymath” and commemorate his crowning achievement.

Matthew Costello, a senior historian at the White House Historical Association, told the event: “Thornton's contribution made possible Washington's vision of a national capital of a country that was destined to become a great empire, one steeped not only in republican ideals, but which projected those through its buildings.”

Gordon Brown, a former US diplomat and biographer of Thornton, said: “The most notable part of his job was his effort to maintain the monumental aspect of the city - the idea [that] this was not just a city, but a representation of republican ideals and the future greatness of America.

“He was a medical doctor who was active in the study of art, botany, mechanical sciences, and he was terribly interested in education. He was a true polymath, and in addition, he was an engaging guy.”