John Milner Architects, Inc.

John Milner Architects is a preservation practice in Chadds Ford, Pennsylvania, working on historic preservation and restoration alongside new traditional residential design. The firm’s work sits at the technically difficult end of preservation, where the problem is rarely appearance and almost always the conflict between original fabric and modern code: egress, accessibility, environmental systems and life safety in buildings that predate all of them. Its most visible recent project is the rehabilitation of the First Bank of the United States in Philadelphia, the oldest bank building in the country, built between 1795 and 1797. The National Park Service reopened the National Historic Landmark on July 1, 2026 after a $43 million rehabilitation and fifty years closed to the public.

Twenty-two people. More than 100 National Historic Landmark properties across better than 35 years of practice. Those two numbers together describe a firm that has concentrated rather than expanded.

The work divides into four areas: Residential Design, Sacred Places, Institutional & Civic, and Historic Preservation. Sacred places is a distinct practice here, not a subheading, which matters because ecclesiastical buildings carry their own combination of structural, acoustic and liturgical constraints on top of the preservation ones.

The methodology is where the firm distinguishes itself from a general architectural practice taking on an old building. A preservation project typically opens with archival research alongside architectural, structural and archaeological investigation, then a conditions assessment, then a written treatment philosophy. Recommendations come after that sequence, not before it. The firm works routinely within the Secretary of the Interior’s Standards for the treatment of historic properties.

That approach is built for the review environment these projects live in. John Milner Architects works regularly with the General Services Administration, the National Park Service, State Historic Preservation Offices, local review boards, and the Advisory Council on Historic Preservation under Section 106. Named projects on the firm’s own pages include the Montgomery County Courthouse, Sandy Hook Lighthouse and the Theodore Roosevelt Birthplace.

Leadership has recently turned over. Christopher Miller, who joined in 1998 and became a principal in 2009, is now Senior Principal, working with Bradley Roeder, Justin Detwiler and Joshua Kiehl. Founders John Milner and Mary Werner DeNadai serve as Principals Emeriti.

The office is at 104 Lakeview Drive in Chadds Ford, and the firm practices along the east coast.