Guarino Guarini (1624–1683), undoubtedly the most original and creative architect of the second half of the seventeenth century, has been the subject of extensive study, particularly in conjunction with the fourth centenary of his birth, the date of the conference published here. But while much has been said about the intellectual figure and his works, it remains unclear why Guarini’s idiosyncratic language had such widespread repercussions, from the Iberian Peninsula to Bohemia. These repercussions were fragmentary and non-linear, conveyed through published designs that were taken up by prioritizing floor plans in some instances and sections in others, while the vaulted systems were not imitated but rather revitalized in new forms construction techniques rooted in local realities. Paradoxically, the fact that this architecture is not based on a specific geocultural context but derives from universal geometric and mathematical principles guarantees widespread, if never complete, repercussions. The effects of Guarini’s influence have fostered important scholarly traditions, which, however, operating within national contexts, have not been closely interconnected. This book also seeks, after a long time, to bring these traditions into mutual understanding, inviting Italian, Czech, and German scholars to discuss and construct a portrait of Guarini more in keeping with the international scope of his legacy.