A castle built for a grocer, Castle Drogo is one of the great buildings of the twentieth century. The grocer was Julius Drew (1856–1931), the co-founder of what was perhaps the largest grocery chain in Britain in its day, so successful that he could retire at the age of 33 and devote himself to his dream. He convinced himself, with the aid of a genealogist, that he was descended from the Drewes of Broadhembury – in 1910 he 'restored' the 'e' to the end of his name – and before that, from the Norman baron Dru (latinised as Drogo) who came over with William the Conqueror. It was a descendant of this Norman baron, Dru or Drogo de Teign, who took his name from the river, and gave it to the parish, Drewsteignton, that was created in the twelfth century. It was there that Julius Drewe bought the Drogo estate in 1910, and started planning to build a castle on a commanding site within it.

His architect, whom he may have chosen on the advice of Edward Hudson, the proprietor of "Country Life", was Edwin Lutyens (1869–1944), who a few years previously remodelled Lindisfarne Castle (National Trust) for Hudson. Despite at first writing to his wife: 'I do wish he didn't want a castle – but just a delicious lovable house with plenty of good large rooms in it', Lutyens rose superbly to the challenge. The house manages to be both an anachronistic castle and of its own day, cunningly giving the impression of a much larger structure than it actually is. Its interiors provide a succession of spare but striking spaces; the whole constructed in dressed local granite. A magnificent building, but expensive to maintain, the house and its 600 acres were generously given to the National Trust in 1974 by his grandson, Anthony Drewe, and his son Christopher – the first twentieth-century house to be accepted.

Julius Drewe had scarcely had the time, but also had lacked the inclination, to put together a collection of pictures. The Murrietas, from whom he had bought his previous house, Wadhurst Hall, East Sussex, had had a vast collection, which their bankruptcy in 1898 had forced them to sell, but though Drewe bought some of the tapestries and exotic Spanish furniture, which he took to Castle Drogo, he did not acquire any of their pictures (one, Tissot's "The Crack Shot", has instead ended up at another National Trust house, Wimpole Hall). Nor do Lutyens's interiors either lend themselves to, or require, an extensive collection of pictures. Those there are, are mostly portraits – sometimes even imaginary ones – of the Drewes, none by notable artists, though that of Julius Drewe in old age, by George Harcourt, with one of the tapestries as a foil to his finely cut suit and waistcoat, is a good one. There is also a full-length portrait, by Charles Hardie, of Drewe as a younger man, kitted out for fishing, in his favourite Burberry; it was after seeing this portrait by Hardie that Lutyens remarked 'At least he could paint boots'. The most intriguing picture hangs over the chimneypiece in the Dining Room and bears the bogus and distorted signature 'Lucas Kranacht 1597'. It was always thought to show Poles and Turks fighting at the siege of Vienna in 1683, but the setting is not that of Vienna, and the picture looks earlier, so it is now thought to represent an episode in some previous campaign.