The palace that stood on this site for three centuries was, by 17th-century reckoning, the most magnificent in Scotland. Seton Palace belonged to the Earls of Winton. Mary, Queen of Scots spent her honeymoon there with Lord Darnley in July 1565, and returned to it in February 1567 after Darnley's murder - playing golf in the fields, William Drury's spies later reported. Kings James VI and Charles I were entertained at the palace. It was burned by the English army in May 1544 after the burning of Edinburgh, and damaged again during the 1715 Jacobite Rising. The Seton family lost their estates after backing the failed rising. By 1780 the palace was a ruin. In 1789 it was demolished entirely, the vaulted ground floor preserved beneath the new building and the old stone reused in its walls.

By December 1789 Adam's working drawings were finished, and the building contract went to Thomas Russell. Construction ran from November 1789 to the summer of 1791. John Patterson, Adam's Clerk of Works in Scotland - who would later become a competent architect in his own right - wrote to Adam on 26 April 1790 confirming that the old palace had been cleared. What rose in its place is one of the most striking examples of Adam's late castle style. The main block is joined by thick screen walls to two wings, with an entrance court enclosed by a further fortified screen wall linking them. A central archway gives access. The exterior reads as defensive. The interior is pure classical Adam - elegant, refined, the work of a man who understood that a castle in 1789 was theatre, not fortification. The house was Category A listed in 1987.

Adjacent to the castle stands Seton Collegiate Church, which survived the demolition of the palace and is now in the care of Historic Environment Scotland. Only the walls of the famous 16th- and 17th-century formal gardens remain from the old palace - that, and the stones now bound into Adam's castle. Entrepreneur Stephen Leach bought Seton Castle in 2007 and undertook a major restoration before selling it in 2019. At that point the estate covered 13.5 acres, the main mansion ran to 18,196 square feet with seven bedrooms, and including the stand-alone cottages the total bedroom count reached thirteen. It was listed in 2024 for £8 million. Robert Adam's final Scottish work continues to do what it was designed to do - shelter the kind of life that can afford such things, in surroundings that whisper of older, grander Scottish dramas.