Did Otto Hermann Kahn, a banker, financier and arts patron, have a rival Long Island estate on his mind as he built his own palatial house, Oheka, in Huntington in 1917?

There’s no written evidence of that, said Joshua Ruff, chief curator of the Long Island Museum of American Art, History and Carriages in Stony Brook, where he has organized the exhibition “Gilding the Coasts: Art and Design of Long Island’s Great Estates.”