In terms of Christian values and ideals in the early centuries CE, Peter is generally regarded as one of the most important apostles, and in particular for the urban community of Rome itself. Peter was used as an icon to convey an ideology to support political goals directly or indirectly. One means for achieving this is through art and architecture. This essay explores this phenomenon by addressing two central enquiries: (i) What does the concept of architectural appropriation imply and how is it integrated in the process of anchoring innovation? How did this relationship develop between the 2nd and 6th centuries? (ii) Who are the protagonists of this development and what was their motive to use Peter as an anchor? This paper describes an approximate model of architectural appropriation deduced from the results obtained in addressing these enquiries. There are several places in the city of Rome associated with Peter: First, of course, the supposed grave site of Peter on the Vatican hill; secondly, the place where Peter and Paul lived and where their skulls, according to legend, were kept during the time of persecution, under the present Basilica of San Sebastiano. In addition to these places, no other physical sites to revere Peter were established in and around Rome, except for San Pietro in Vincoli. This article, however, focuses exclusively on the Vatican and San Sebastiano, as there are many architectural activities to retrace. Architectural appropriation in this context means the intentional use of architecture or architectural decoration in order to achieve particular political or societal goals. This observation is closely linked to the concept of anchoring innovation. In fact, architectural appropriation can be a kind of anchorage. The conceptual basis of anchoring was laid down by Sluiter in 2017; she stated that anchoring innovation is the successful implementation of something new to a defined social group by conveying that this innovation is based on something old and long known.1 The same can be said of architectural appropriation: it