How to deal with historic buildings has long been a core issue of the international architectural discourse. Herzog & de Meuron began addressing the potential of existing structures very early on: the maintenance and alteration of buildings are among the key strategies of the architects. For the Park Avenue Armoury in New York, Herzog & de Meuron have designed a new model for dealing with monuments. The historical building was opened in 1881 on the Upper East Side of Manhattan as a meeting place and training ground for the National Guard, and boasts a rich mixture of different styles. Herzog & de Meuron developed a multifaceted strategy for the transformation of the building, now used as a cultural centre, that allows for a combination of restoration, transformation, and innovation. From the exposing of historic structures to the addition of new elements, the architecture gained new vibrancy from the considered entanglement of different aspects. In the current debate, this departure from the practice of historic preservation in the United States is, beyond its value as an actual example, a unique contribution that unfolds in close reference to material. It is exemplary and groundbreaking.