A conservation plan was prepared for Fonthill, Henry Chapman Mercer’s concrete masterpiece in Doylestown, Pennsylvania which was built between 1908 and 1912. The Plan, commissioned by the Bucks County Historical Society, addressed the short and long-term challenges of maintaining the integrity of the building’s concrete structure and its cast-in-place decorative arts collections. The primary objective was to clearly understand Fonthill’s complex and interrelated components and systems, and to identify the critical issues and formulate a short and long-range plan for addressing those issues. Construction documents for phased restoration work followed the initial conservation plan.