J. P. Morgan was one of the most active art collectors of his time. Both his house at 36th Street and Madison Avenue and his house in London were overflowing, so in order to consolidate his collection of rare books and priceless manuscripts, he built this wondertful building in what had been a garden behind his house. The exterior is made from blocks of stone laid without mortar, fitted so closely together that a knife blade couldn’t be inserted between them. The interior contains three grand rooms: an elaborate entrance rotunda, a library to its east lined with three tiers of books, and Morgan’s study on the west side. It was Morgan’s intention that his library would make his collection permanently available for âœthe pleasure of the American people,â and this core building is exactly as he left it.