Marriott City Hall Annex

Location: Philadelphia, PA
Renovation Architect: Stantec Architecture, Inc.

O'Donnell & Naccarato provided structural engineering services for the renovation of the historic, 17-story Philadelphia City Hall Annex building, converting the dilapidated structure built in 1926 into a 498-room hotel. Listed on the prestigious National Register of Historic Places, the 395,000 SF Courtyard Philadelphia City Hall Annex offers a full service restaurant and 10,000 SF of banquet facilities.

The largest challenge posed by the conversion project was creating a loading dock by cutting and removing the ground-level portion of an existing exterior full-height building column, resupporting the column and limestone facade loads above and redirecting them around the new fifty-foot dock door opening. Other notable structural designs included supporting a new indoor pool and spa area atop an existing framed floor, adding a mechanical room above the low roof directly above the new restaurant, and restoring the corroded penthouse cornice support steel.

The Marriott Courtyard City Hall Annex received the 2001 Preservation Alliance of Greater Philadelphia Honor Award and The Green Building Contractors Association’s Honorable Mention for Best Historic Renovation.