Horace Trumbauer is one of the most unexpected figures in American architecture. He hailed from humble origins. A salesman’s son, painfully shy, and never “clubbable,” he became the most sought-after architect among the haut monde of the late Gilded Age. He entered the architectural profession as an office boy in the firm of Philadelphia’s renowned Hewitt brothers. He never attended the Ecole des Beaux-Arts – or any other architecture school. Yet no other American architect ever excelled more than Trumbauer in the mastery of the forms of French classical architecture. And though he worked largely within an 18th-century vocabulary, no American architect created buildings so distinctively his own.

Trumbauer worked out of Philadelphia, but designed many buildings elsewhere. Among these were buildings at the North Carolina campus of Duke University. In New York, Trumbauer designed the Fifth Avenue mansion of that university’s benefactor, James Buchanan Duke, the tobacco (Lucky Strike) tycoon. Located at the northeast corner of 78th Street, the Duke mansion now serves as New York University’s Institute of Fine Arts. It is as beautiful a house as ever graced this city.

Trumbauer’s genius lay in his sense of proportion. We see this in his windows. His window openings are large or elongated in the 18thcentury French manner. Yet he could squeeze and pull those openings in such a way as to make it seem like other architects just phoned it in. The way the window frames, balustrades, belt courses, quoins, and cornices relate to one another, latitudinally and in degree of relief, and the way plain raised vertical panels separate the windows, are done with such a deft touch as to make one think he had an innate sense of proportion not given by God to other architects.

Note also the complexity of the crowning sequence, the way the bracketed cornice and the fine rooftop balustrade resolve into a sensational pediment, with a dentilated cornice providing a frame for delicious figure sculpture. The degree of projection of the central section – with Doric columns below, Ionic above – is absolutely right for a Manhattan street, monumentality modulated as streetline architecture. It is as close to perfection as New York architecture gets. The putative model was Etienne Laclotte’s Hotel Labottiere in Bordeaux, but Trumbauer’s is the greater work.

The Duke house’s severity is deceptive. Sundry subtleties work in perfect balance to create this astonishing elegance.

The house, faced in a luscious white limestone, rose in 1909-12. Michael Kathrens, in his indispensable book “American Splendor” (2002), on Trumbauer, says Duke built the house as a wedding gift to his second wife, Nanaline. The Dukes moved in just before the birth of their daughter, Doris. Duke died in 1925. The press pounced upon every exploit of Doris’s, not least her 1935 wedding, in the house’s library facing Fifth Avenue. Nanaline lived in the house until 1957,when she and Doris deeded it to NYU, who hired Venturi, Cope & Lippincott to renovate it. NYU possesses no building remotely so fine.