09/09/2026
SITIO is thrilled to welcome Elizabeth Mahon who has joined the firm as Managing Principal, effective September 1. The appointment pairs her design experience with a focus on growing SITIO's client relationships and expanding into new markets.
In her new role, Mahon will work closely on the design and development of individual projects, collaborating directly with the firm's Principals and design team. Her arrival signals a deliberate next step for SITIO. After a decade of delivering large-scale work as a design and community focused practice, the firm is positioning to further broaden its reach both locally and nationally.
“Elizabeth brings the design leadership and market experience SITIO values at this stage of our growth,” said Antonio Fiol-Silva, FAIA, founding principal of SITIO. “She builds client relationships and an expert in the kind of complex, high-profile work that aligns with our practice, and she shares our belief that great design comes from close, sustained collaboration with clients and communities. As we celebrate ten years of SITIO, it is exciting to have her join our team as we look ahead to the next ten.”
Mahon joins SITIO after a decade at HDR, where she served as Managing Principal and built the firm's Philadelphia architecture studio from the ground up, growing it to 50 people and expanding its work across higher education, life science, healthcare and civic projects. Earlier in her career, she was a member of IM Pei’s Paris office working on the Louvre Museum expansion and worked with other national design-focused firms including Pelli Clarke & Partners, William Rawn Associates, and in Philadelphia, Ballinger. Her recent work includes 3025 JFK Boulevard, a mixed-use life science, residential and retail project developed for Brandywine Realty Trust; the library and learning commons renovation in the Community College of Philadelphia's Mint Building; and the CHOP Center for Advanced Behavioral Health.
“After building and running a large studio, I was ready to get back to what I enjoy most about architecture; the design itself and the day-to-day interactions with clients,” said Elizabeth Mahon, AIA, Managing Principal of SITIO. “SITIO's culture and its focus on community and placemaking made this the right move at the right time. There's tremendous opportunity to build on the diversity of work the firm does, and I am thrilled to be part of the team."
Mahon holds bachelor’s degrees in architecture and finance from the University of Pennsylvania and a Master of Architecture from Yale University.
