Dundas House, Edinburgh was designed by Sir William Chambers in 1771. Its exterior design is an exact replica of Marble Hill House apart from using the Corinthian Order rather than the Ionic and it is also built on a slightly larger scale. Like Marble Hill, the fenestration is 1-3-1 and the centre is articulated by four pilasters crowned by a pediment, with the first floor windows emphasised to show that the piano nobile is on the first floor. Like Marble Hill, the ground floor is rusticated. The design of the interior was originally close to that of Marble Hill, based on a tripartite plan; but after being taken over by the Royal Bank of Scotland (1825) the interior was altered substantially over the years to meet the Bank’s needs.
It was built for Sir Lawrence Dundas, one of the MPs for Edinburgh, who had supported the Act of Parliament to extend Edinburgh and allow the building of what is known as the New Town. Dundas was also the Governor of the Royal Bank of Scotland. Coming from a relatively modest background, he made a huge fortune as an army contractor. As well as this house in Edinburgh, he had a house in London and the Orkneys and an estate in Yorkshire.
The reason he employed Sir William Chambers, King George III’s favourite architect, was probably to show “he had arrived”. Chambers had already designed Duddingston House in Edinburgh for the Earl Abercorn in 1763. Dundas House is generally regarded as the finest in the New Town and is likely that Dundas, a self made man, wished it to display his wealth.
A more difficult question is why Chambers, a distinguished architect in his own right and already using the new Neo-Classical style (at Duddingston House), copied the design of a house in the Palladian style, when this style was actually going out of fashion. The answer may possibly lie in the fact that Chambers leased Whitton Park in 1765, which was designed by Robert Morris for the Duke of Argyll. Chambers, having leased this house, was probably paying homage to Roger Morris by designing Dundas House in the style of Marble Hill House.
For more information take a look at the Atlas Obscura entry for Dundas House.