After the 1853 fire that destroyed the original building, the school established a design competition to select an architect. Benefactor Harriet L. Packer chose the design of celebrated architect Minard Lafever.

Lafever had a reputation for creating notable buildings, including a number of churches in New York City and Brooklyn. Packer would be Lafever’s final commission, as the school was opened just fifteen days before the architect’s death.

Designed in the Gothic Revival style, the original Packer building—now known as Founder’s Hall—consisted of classrooms, a chapel, and two towers. The famous campuses of Oxford and Cambridge Universities in England inspired Lafever.

The Packer chapel was and remains one of the most architecturally interesting and important areas of Packer’s campus. It occupies space on the third and fourth floors of the school and features Gothic arches and nine striking stained-glass windows produced by the famed Tiffany Studios.

The school also originally included a small observatory housed in one of its towers. However, following the extension of the subway system under Joralemon Street in 1900, which caused many rumbles, and the proliferation of artificial lighting, stargazing in Brooklyn eventually became impossible.

In the 1880s, a new gymnasium and a science hall that included lab space were added. These additions reflected a growing interest in physical education and science education for women. Alumnae Hall, named for its financing by former Packer students, was added to the building complex in 1907, while in 1957 Pratt Hall was added. This building houses a gymnasium, theater, and classrooms and was financed by former student Katherine Sloan Pratt.

The Packer Collegiate Institute continues to undergo changes as it responds to the needs of its community. In 1969, St. Ann’s Church—situated next door to Packer—was purchased and in 2003, its renovated space became home to the Packer middle school.