Renewal of the structure’s “envelope” buttresses its long-term structural and historical integrity
The Hunnewell Building at the Arnold Arboretum, a historic museum and administration complex constructed in 1892, stands as a testament to architectural elegance and botanical significance. Listed on the National Register of Historic Places and designated as a National Historic Landmark, the building has been a cornerstone of the Arboretum’s operations and public education mission for more than a century. This winter, contractors finalized the first phase of major renovations to the Hunnewell Building to preserve its historic integrity and sustain its use by staff and the public for years to come.
After more than a century of use and exposure to Boston’s weather extremes, the Hunnewell Building required comprehensive masonry, window, and roof restoration. Additionally, for much of its life the building was covered in ivy, a handsome and distinguishing characteristic of many historical structures in Boston which over time can have the significant downside of damaging masonry, mortar, and gutters. An envelope study completed by Structures North Engineering Consultants in 2019 identified critical restoration needs and recommended a phased approach to halt further deterioration. The design and preconstruction services from 2022-23, as well as the restoration phase that launched in April 2024, were completely funded through philanthropic support.
Renovations—which wrapped up in late November 2024—focused primarily on essential exterior work, including membrane roof replacement, slate replacement and repair, copper gutter replacement, masonry restoration at the building’s cornice, select window lintel replacement, and selective repointing at all elevations. Sourcing the right materials, such as the “North Country Black” slate for the roof from Quebec, helped maintain the quality and historical integrity of the renewal effort. Sustainable building methods were employed whenever possible. This included salvage of original materials, as well as replacing membrane roof surfaces with reflective white PVC to reduce solar absorption and thermal radiation.
“This critical project marks an important milestone in the life of the Hunnewell Building,” said Danny Schissler, head of operations and project management at the Arboretum. “Masonry restoration is tedious work requiring uncompromising attention to detail. Seeing every brick and slate removed, cleaned, stockpiled, and meticulously reinstalled is truly humbling, and gives one a great appreciation for the craftsmanship and care put into the original construction.”
A critical aspect of the renovation was protecting the surrounding landscape and living collections. In consultation with the Arboretum’s horticultural and landscape team, a comprehensive site and plant protection plan was developed. This included the selective removal and relocation of specific plants, designing perimeter fencing and scaffolding to protect mature trees, and pruning or tying back branches in the construction zone. Preparation work also involved lining a century-old clay drainpipe, regrading the southeast perimeter, and installing a drainage system. Protective measures safeguarded the building’s historic façade, entrances, and mechanical equipment, ensuring public safety and allowing the Hunnewell Building to remain open without disruption.
“We are fortunate to have had the opportunity to preserve this remarkable building—an architectural gem for the people of Boston that harmonizes with the natural grandeur of Olmsted’s surrounding landscape—for future generations of Arboretum staff and visitors,” said Arnold Arboretum Director William (Ned) Friedman. “We are grateful to the Powder Mill Foundation for their leadership support in making this critical renewal possible.” Funding from the Powder Mill Foundation was made in memory of Josephine and Louis J. Appell Jr., longtime supporters of the Arboretum whose philanthropic support of the institution included funding the creation and installation of the scale model of the landscape that has delighted the public at the Hunnewell Building Visitor Center since the 1990s.
Situated just inside the Arborway entrance, the Hunnewell Building was originally designed by architect Alexander Wadsworth Longfellow, Jr. and funded by its namesake, railroad financier and philanthropist H. H. Hunnewell. The grand brick structure with a finished hip-roofed attic and full basement was constructed to serve the managerial, archival, and educational needs of Harvard’s museum of trees. Over the years, the building has housed several Arboretum departments, including horticulture, public programs, advancement, and curation. It remains in continuous, daily use, with a visitor center and lecture hall on the first floor open to the public, an herbarium of cultivated plants on the second floor, and the Arnold Arboretum Horticultural Library and Archives (open weekdays to the public by appointment) on the third floor.
Within a few decades of its completion, the Hunnewell Building nearly doubled in size with the construction of a four-story, flat-roofed rear section for housing laboratories, offices, and collections storage. A three-story link section was also constructed to connect the two parts, aligning the floors seamlessly. Major renovations in 1993 further modernized the building with a stair tower, elevator, new roof sections, interior updates, and improvements for public accessibility.
The 2024 envelope renovations have had a significant impact in renewing the Arboretum’s beloved “museum building” and set a foundation for future phases of renewal work. Over the next 7-10 years, the Arboretum aims to complete additional restoration projects to ensure the Hunnewell Building continues to serve its vital role in the Arboretum’s mission and remains a cherished landmark for Boston and the horticultural world.