The redevelopment of One Madison Avenue involved a multi-phase foundation improvement and enlargement to facilitate the partial demolition and construction of a new midrise office tower while maintaining the façade of the original structure. During phase 1, Standard Concrete & Excavation was responsible for footing and column enlargements throughout the structure to facilitate the core demolition. During phase 2, a new foundation was then excavated and constructed within the existing building core. This logistically challenging scope involved rock excavation, dewatering, rock anchor drilling and a large mass concrete foundation mat, with areas exceeding 15’ of total concrete thickness. Standard Concrete & Excavation was able to facilitate the mobilization of large rock breaking equipment inside of the structure and instituted a dual-shift construction schedule in order to bring the project to completion ahead of schedule.