The Flatiron

Location: Boulder, CO | Size: 415,000 SF | Estimated Completion: 2029

Sopher Sparn is leading the design of a transit-oriented, mixed-use development at the corner of 55th Street and Arapahoe Avenue in Boulder. Designed as a welcoming neighborhood hub, the five-story project will introduce approximately 300 residential units in a variety of sizes, supporting the City’s housing goals while aligning with the Station Area Master Plan and East Boulder Subcommunity Plan.

Replacing the existing buildings at 5501 and 5505 Arapahoe, the project balances increased density with thoughtful massing, pedestrian-scaled design, and strong connections to transit. Active ground-floor uses bring energy to the street, including space for Premier Members Credit Union, allowing the longtime neighborhood institution to remain on site. Together, the residential, retail, and public spaces create a walkable, community-focused development that strengthens East Boulder’s evolving urban fabric.

Rendering of The Flatiron in Boulder, CO showing a five-story mixed-use building with residential units, retail spaces, and landscaped sidewalks at street level. -Designed by Sopher Sparn Architects
The Flatiron mixed-use development in Boulder, CO viewed from the corner of 55th Street and Arapahoe Avenue, highlighting pedestrian pathways, greenery, and street-level activity.
Street-level rendering of The Flatiron in Boulder, CO featuring modern brick facade, retail storefronts, and community-focused design with outdoor seating and trees
Rendering of The Flatiron in Boulder, CO showing the building entrance, landscaped areas, and active pedestrian spaces connecting the mixed-use development to the neighborhood.
Rendering of The Flatiron mixed-use project in Boulder, CO with five-story residential units, and integration with the surrounding urban fabric.
← Back to On The Boards