social capital; Like a great beauty returning to town, the Morgan Library is causing a fever of interest this spring.

Byline: William Norwich

After shutting its doors nearly three years ago for a $102 million expansion designed by the architect Renzo Piano, the Morgan Library reopens this month to the public, who will finally see what the addition of about 75,000 square feet means for this venerable institution.

A bit of background for the uninitiated: Designed by Charles McKim, the original Italian Renaissance-style palazzo was completed in 1906 as a private library for Gilded Age financier J. Pierpont Morgan, built on the street where he lived, East Thirty-sixth Street at Madison Avenue.

Of course, it never was your typical library. For instance, here was the world's chicest librarian, Belle Greene, whose father was the first African-American man to graduate Harvard. To care for valuables like the Gutenberg Bibles, Belle wore jewels and couture dresses to work.

"Just because I am a librarian doesn't mean I have to dress like one," she explained.

Morgan died in 1913. In 1924, his son, J. P. Morgan, Jr., concluded that the family's remarkable collection of rare art and manuscripts was too important to be held in private hands and established the library as a public institution, endowed by the Morgan family and maintained by a board of trustees. And maintain it they did, building the library's collection, making it a welcoming place for European art historians to study, especially during World War II, never altering Mr. Morgan's original rooms, including his red-velvet study ("Morgan red," as it is known), and keeping the philistines, as it were, at the gate, an ornamented bronze fence you've probably ...