Millennium Partners Listed The Burnham Office Space
The firm has placed 244,000 square feet of office space at 10 Summer Street on the market for potential new tenants.
Updated on Sept. 30, 2026 in Commercial
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Millennium Partners has officially listed 244,000 square feet of vacant office space across six floors at 10 Summer Street, a property widely known as The Burnham. The space became available after Arnold Worldwide relocated its operations to 5 Necco Street in 2024.
Why it matters
The listing enters a competitive commercial real estate environment where developers are increasingly forced to offer significant concessions to attract occupants. Millennium Partners is attempting to differentiate the historic property by leveraging amenity access through its Winthrop Center development.
The property offers 244,000 square feet of total space with a minimum lease requirement of 35,000 square feet per floor. The building, which first opened in 1912, features 10-foot windows designed to maximize natural light.
The players
Millennium Partners
This real estate development firm specializes in luxury mixed-use projects and urban redevelopment initiatives.
Arnold Worldwide
This is a global creative advertising agency that previously served as the anchor tenant for the office space.
CBRE
This company is a global commercial real estate services and investment firm that facilitates property leasing.
The details
CBRE is managing the leasing campaign for the six-floor block within the historic department store site, which Millennium Partners acquired in 2012. The developer intends to secure a single large anchor tenant to fill the vacancy left by Arnold Worldwide.
Timeline
The Burnham building originally opened in 1912.
Millennium Partners acquired the property in 2012.
Arnold Worldwide moved out of the space in 2024.
The Boston central business district vacancy rate reached 20.1 percent in Q2 2026.
Culture Shift
This listing reflects the broader evolution of historic urban assets struggling to compete with modern office developments in a post-pandemic market. It highlights the shift toward amenity-driven leasing strategies as developers attempt to lure companies away from newer, specialized hubs.
The availability of this massive amount of space could lead to increased traffic or business activity near the Summer Street corridor depending on the size of the tenant that eventually signs a lease. Local workers and residents may see changes in the surrounding retail ecosystem if a new anchor tenant moves in to occupy the upper floors.
The takeaway
Large-scale office listings in historic buildings are increasingly bundled with premium amenities to compete with new construction in a tenant-favorable market. Tenants searching for space in the current climate should prioritize evaluating the specific concessions and amenity packages offered by landlords.
Further reading
For more information on the current state of local workspace trends, visit Boston Commercial.
Source note: This article includes information reported by Banker & Tradesman.
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