Despite the construction of Reunion Hall in 1870, the College of New Jersey continued to experience an acute shortage of dormitory rooms. Enrollment rose steadily throughout the 1870s, and President McCosh eventually constructed five more dormitories. The most important and architecturally interesting of these structures was Witherspoon Hall, commissioned in 1875 and occupied two years later.

Designed by William A. Potter and Robert H. Robertson, Witherspoon was another in the series of High Victorian Gothic buildings at Princeton that included the John C. Green School of Science and Chancellor Green Library. More significant than choice of style, however, was Witherspoon's placement on the far western side of the campus and the unparalleled luxury of its accommodations. Both of these factors reflected dramatic changes in the College and its perception of itself.

Witherspoon's location, to the west of Clio and to the south of the Bonner-Marquand Gymnasium, was influenced by the advent of the railroad. For more than a century, Nassau Street had been the main thoroughfare and access route to Princeton. But the construction of a new railroad station, built in the 1870s at the base of what is now Blair Arch, changed all that. The primary entrance to the campus immediately shifted from Nassau Street to the west side of the campus.

Until Blair and Little Halls were built some 20 years later, Witherspoon Hall was the first building newcomers saw upon arriving on campus by train. Accordingly, McCosh wanted a building of sufficient scale and style to impress visitors. Looming five stories, and featuring prominent towers and other bold details, the design for Witherspoon certainly fit the bill.

But McCosh had other motives in constructing Witherspoon. In the wake of the Civil War, the College attracted a more affluent student population. The spartan facilities of many of the college's dormitories were simply unpalatable to this new type of undergraduate. With amenities such as waterclosets on every floor, dumbwaiters, and special corridors and rooms for servants, Witherspoon was tailored to meet the needs of these wealthy students.

In fact, Witherspoon was considered the most modern and elegant dormitory of its time. Harper's Weekly declared the structure "one of the most commanding college buildings in the world." Another contemporary observer wrote that it was "the most beautiful and luxurious college dormitory in the country."

Shaped like an "H", the building accommodated 140 students in 80 rooms. The ground level was constructed of dark, ashlar stone from Newark, while the floors above were made of blue-gray Pennsylvania marble set off with bands of Newark stone. In this regard, Witherspoon was more restrained than some of the aggressively polychromatic High Victorian Gothic buildings of the period.

The roof was broken by numerous gables and dormers, and each floor had a different style of windows. The ridge line of the roof was ornamented with stone crockets and the west facade included an unmatched balcony.

Large, asymmetrical towers rose from the west end of the structure, while the southwest corner featured a turret with a conical cap.

Other interesting details included the rounded arches on the entrance porch, spandrels above the windows, and textured panels of stone on the facade. And according to one contemporary account, "It was planned with special reference to the sun's course, the design being to allow every room a chance at the sunshine during some portion of the day."

As originally designed, the interior of Witherspoon was really four separate buildings, each with a separate entryway. At the same time, the distinctive entrance porch on the north side, which connects the east and west wings of the building, unifies the exterior of structure.

Although extremely popular with students at first, Witherspoon fell out of favor once the Collegiate Gothic style dormitories began to be built in the 1890s. Once the most expensive and sought-after accommodations on campus, Witherspoon gradually became one of the least desirable addresses at Princeton. The great western tower, damaged by storms, was removed in the 1940s.

In 1969, the top three floors of the building were condemned as a fire hazard. A year later, the first two floors served as a home for women undergraduates while Brown Hall was renovated. There was talk of tearing down the building, but after an energetic "Save our 'Spoon" campaign by alumni and students, the Trustees decided to renovate it instead. Over the summer of 1974, the University installed a sprinkler system, replaced bathrooms, improved fire egress, and otherwise modernized the old dormitory.