Of the surviving McCosh-era buildings, the Chancellor Green Library has best stood the test of time and changing taste. This may seem counter-intuitive, as 20th-century Princeton has generally frowned on the High Victorian Gothic style, and Chancellor Green was perhaps the most pronounced example of the style erected on the campus.

But it was also the most successful. A symmetrical building featuring strong geometric forms, rich ornamentation, and a marvelous octagonal rotunda (the ceiling in Chancellor Green Library is one of the most striking structures in Princeton), the library is characterized by its own grace and integrity.

Designed by William A. Potter, Chancellor Green Library was commissioned in the spring of 1871 and was underwritten by McCosh's great patron, John C. Green. The building was named for Green's brother, Henry W. Green, class of 1820, a trustee of the College and Chancellor of New Jersey. The foundation was laid by November 1871, and the walls finished in time for Commencement the following spring. It was dedicated in May 1873 and its costs exceeded $100,000.

The first purpose-built library on the campus, Chancellor Green Library reflects one of McCosh's top academic priorities. When McCosh arrived in Princeton in 1868, he was appalled at the state of the College's library, which was open only one hour per week. If the College were to improve its academic stature, it clearly needed a better library.

In December 1870, he sounded out the Trustees about raising funds to construct a new library. It was the fourth building that McCosh initiated and, as with the others, it addressed a critical gap in the College's physical plant. First came a new gymnasium to appease and occupy the students, followed by a classroom building and a dormitory necessary to meet the demands of the rising enrollment. The new library had to wait, but its character and placement speak to its importance in McCosh's overall scheme.

Conscious of the symbolism of location, McCosh placed the library at the new heart of the expanding campus. Philosophical Hall, which stood immediately northeast of Nassau Hall, was demolished to make way for the new structure. Proudly facing Nassau Street, the library formed the western end of the quadrangle of academic buildings that included Dickinson Hall and the John C. Green School of Science.

The central section of library is a two-story octagonal rotunda, flanked to the east and west by matching, single-story reading rooms. Before the construction of Pyne Library in the 1890s, the entrances were in passageways that connected the reading rooms to the rotunda. These arched entrances, not used today, included such rich details as polished granite columns and capitals that are carved into stacks of books.

Potter's choice of a rotunda format, and the resulting radial arrangement of book stacks, drew on several precedents. Jefferson's rotunda at the University of Virginia (1823) used radial stacks, as did the library in the Houses of Parliament in Ottawa. The world's most famous reading room, in the British Museum, may also have inspired the design of the library.

What set Chancellor Green apart stylistically from other buildings of this period on campus was its symmetrical design. Unlike the asymmetry found in Witherspoon and the School of Science, for example, Chancellor Green Library featured uniform, repeating patterns of geometric shapes -- stars, circles, and octagons -- on the exterior and interior. The library has numerous arches, also symmetrical.

Contrast these arches on the library, for example, with the main facade of the School of Science.

The interior of the rotunda remains the library's chief architectural achievement, however. Potter's biographer describes this impressive space:

A diadem set with stained glass windows, it crowns the segmented and buttressed walls. Eight cross gables, each containing a large fan-shaped window, intersect the main roof, which culminates in an octagonal dome light. The domical roofs of the central building and wings are banded by narrow clerestories like Edward T. Potter's [William Potter's brother, also an architect] churches, and delicate iron crests decorate the roofs.

When built, Chancellor Green could hold 150,000 books -- or three times the extent of the College's holdings in 1870 -- and had seating for 100 students. Within 15 years, though, Chancellor Green was overflowing, reflecting both the dramatic expansion of the College and in academic learning. Relief came with the erection of Pyne Library in 1897.

Chancellor Green's rotunda was attached to the new library by a "hyphen" and served as the new reading room for the library. In 1913, the smaller west reading room was converted into the Trustee's meeting room by the firm of Cram, Goodhue, and Ferguson, complete with a carved oak ceiling, pointed windows, and rosewood paneling.

Since Firestone Library was built, Chancellor Green has served as a coffee house, student pub, and part of the student center. To help make way for the new library, the Joseph Henry House was moved in front of Chancellor Green, which blocked the fine perspective from Nassau Street. Today, a row of trees also helps screen the building from view.