Schinkel / Campo Marzio connection
Yesterday, noticed a similarity between the plans of the monuments to Julius Caesar and Augustus in the Area Martis and one of the monuments to Friedrich the Great by Schinkel. Moreover, there is also a similarity between the round rooms within the Xystus Agrippinae and the lower level of the rotunda of the Altes Museum. These similarities raise a curious as to whether Schinkel was inspired or influenced by the Piranesi plan diagrams. (Schinkel did spend time in Rome, and there is also the link to Piranesi via Durand.)
In any case, it is an interesting coincidence, and whether or not Schinkel actually noticed the plans in the Ichnographia of the Campo Marzio may not be all that important because, regardless of the actual historical truth, the connection is seen now and perhaps even a comment on the fluidity of architectural history.