This thesis explores the design of a supertall tower in New York (through an adaptive transformation of an existing building), by employing circular design principles and design-for-disassembly strategies. The research posits that circular design, in an age of resource scarcity and depletion, affords a more sustainable, integrated and wholistic approach to considering architectural practice. The research includes research into circular design, and builds on work experience at 3XN/GXN, to help situate circular design and its emphasis on Materials, Service Life, Standards, Connections and Deconstruction, as a method of thinking through architectural design and construction. This structure is used as a design lens for a transformation of the (slated to be torn-down and replaced) JP Morgan-Chase building on Park Avenue. The design project explores ideas of green infrastructure, carbon neutrality, flexibility and adaptability and more fully integrated social and public spaces into a supernal tower.