geek. lego enthusiast. art lover. tinkerer.
Kerri Callahan’s career spans a diverse range of roles, all rooted in her background in interior architecture, with lighting design serving as a central thread throughout her 25-year professional journey. She has cultivated a distinctive blend of leadership, design, construction, and project management expertise, with lighting as a consistent and defining focus.
A proud graduate of the University of Illinois at Chicago’s architecture program, Kerri’s first love is the city of Chicago and its architecture—an early inspiration that continues to inform her design perspective. This deep-rooted appreciation for the built environment has shaped her career and passion for how spaces are experienced, especially through light.
As a seasoned architect and lighting designer, Kerri brings comprehensive experience across all aspects of design, with a particular passion and specialization in lighting. She is a recognized subject matter expert in exhibition and architectural lighting, and deeply understands how light shapes spatial perception, mood, and experience. Her lighting work is grounded in a philosophy that balances aesthetics, function, and sustainability—creating atmospheres that elevate architecture while prioritizing energy efficiency and long-term performance.
Kerri’s portfolio includes numerous high-profile interior renovations where her strong design sensibility and technical lighting expertise have delivered thoughtful, innovative environments. Known for her precision and creativity, she reveals the character of a space through light while skillfully navigating complex project constraints—such as phased construction, evolving scopes, and tight budgets. A true collaborator, Kerri excels at translating user needs into lighting strategies that integrate seamlessly with Universal Design and sustainability principles, resulting in spaces that are inclusive, resilient, and impactful.
Outside the professional world, Kerri enjoys traveling, spending time with her loyal pup Dirty Harry, and exploring her passion for art and fashion.

book lover. reality tv enthusiast. maker and baker.
Erin Held’s career reflects a deep commitment to the artistry and precision of architectural lighting design. With more than a decade of experience leading creative teams, she brings a dynamic blend of vision, technical expertise, and mentorship to her work.
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At Polymath Design, Erin helps drive the creative direction and conceptual development of high-profile projects across the hospitality, commercial, and cultural sectors. She guides each project from initial concept through construction administration, ensuring every detail aligns with design excellence, project budgets, and timelines. Known for her collaborative approach, Erin fosters professional growth within her teams while maintaining a steadfast dedication to high design standards.
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Before joining Polymath, Erin served as a Design Principal at Charter Sills, where she helped shape some of the firm’s most notable projects including the renovation of the Chicago Union Station Great Hall and the new Chicago Park District Headquarters. An enthusiastic partner to designers and architects alike, Erin focuses on using illumination to amplify and elevate the best elements of every project, enhancing spaces with thoughtful and strategic lighting solutions.
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Erin’s work has been recognized with major industry accolades, including being named the 2020 LIT Lighting Design Awards Lighting Designer of the Year. She is also the recipient of the prestigious Edwin F. Guth IES Illumination Award of Excellence.
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She holds a Bachelor of Fine Arts from Millikin University and a Master of Fine Arts from Columbia College Chicago.
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Outside of the studio, Erin is a book lover, cat mama, British period drama aficionado, and closet organization enthusiast.


polymath press and other stuff...
Case Study - Color Tunable Lighting at the Art Institute of Chicago
Illuminating Art for Emotive Effect - St. Mark's Chapel, Geneva, IL
2022 AIA Chicago Design Excellence: Interior Arch S; University of Chicago; BarDAVID
2018 AIA Chicago Design Excellence: Distinguished Building; University of Chicago Campus North
2017 1st International Museum Lighting Symposium; Speaker; Color Tunable LEDs
2016 AIA Chicago Small Project Award: Honor Award; Writers Theatre
2015 IES Chicago Illumination Award of Merit; Swift & Sons
2014 IES Chicago Section Award; Hillshire Brands Headquarters
2014 IES Chicago Illumination Awards, Award of Merit; Hillshire Brands Headquarters
2007 AIA Chicago Sustainable Design Award ; Access Living Headquarters
2007 AIA Chicago Sustainable Design Award; Access Living Headquarters
2007 Barrier-Free America Award; Access Living Headquarters
2007 Neocon Presenter; Access Living; Universal Design for All
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American Institute of Architects (AIA), Member
The International Association for Lighting Designers (IALD), Member
Illumination Engineering Society (IES), Member
WBE (Women-Owned Business Enterprise) Certified - City of Chicago