Sankei Building Acquires Stake in Boston Office Building for Residential Conversion
The Sankei Building acquired a stake in 294 Washington Street (historically known as the Old South Building), an existing office building in downtown Boston, Massachusetts, in June 2026. Together with local developer Synergy, the company will convert the building into a rental residential property with a planned total of 255 units. Construction is scheduled to start in January 2027, with completion planned for the second half of 2028.
The property is located in the Downtown Crossing / Financial District area, with four major subway lines and four stations nearby, offering strong transit accessibility. Completed in 1903, the building has 11 floors above ground and two below, with a gross floor area of approximately 6,182 tsubo (approx. 220,000 sq. ft.). The project will preserve and restore the building's classical facade and design details while creating 127 studio units, 98 one-bedroom units and 30 two-bedroom units, along with retail space on the ground floor.
The City of Boston operates an "Office-to-Residential Conversion Program" to encourage the conversion of offices with rising vacancy into housing. The program supports development through tax incentives and expedited review procedures, and as of March 2026, conversions of 29 buildings into more than 1,700 housing units were planned. This project is the largest among properties covered by the program.
The Sankei Building has previously participated in residential developments in areas including the Seattle suburbs, Los Angeles, Phoenix and Portland. This project is likewise part of the company's residential business being advanced across the United States.
Key Facts
- Property Name: 294 Washington Street (historically known as the Old South Building)
- Joint Developers: THE SANKEI BUILDING CO., LTD. / Synergy
- Location: 294 Washington Street, Boston, MA 02108
- Completion (existing building): 1903
- Sankei Building's Stake Acquisition: June 2026
- Conversion Construction Start: January 2027 (scheduled)
- Conversion Completion: Second half of 2028 (scheduled)
- Use: Rental residential and retail (existing use: office)
- Number of Floors: 11F / B2 (steel-frame construction)
- Site Area: approximately 694 tsubo (approx. 24,700 sq. ft.)
- Gross Floor Area: approximately 6,182 tsubo (approx. 220,000 sq. ft.)
- Total Units: 255 planned (including 52 income-restricted units)
- Unit Mix: 127 studio units / 98 one-bedroom units / 30 two-bedroom units
