Carlo Maderno (1556-1629) was the successor and nephew of Domenico Fontana. He had assisted his uncle in the placement of several obelisks, during the wave of city planning. After becoming a more established architect he was put to work on the renovation of S. Susanna in Rome (1597-1603).
Faced with the now common situation of seamlessly applying a temple front on an irregular Medieval structure, Maderno looked to Vignola's original design of Il Gesu for ideas, using volutes to connect the two stories and topping the whole with a pediment. However, he made the design his own by giving strength and force to the classical orders. Using ornamental build up, layers are created giving a sense of projection and recession. Especially in the upper story, where the columns have shifted from being engaged on the lower to thick pilasters reaching out on the top story.
Maderno is also important because of his work on St. Peter's. In 1603 he was appointed by Pope Paul V to succeed della Porta's position as Architect of St. Peter's. Several years into his residency, Maderno began to make decisions that would complete the construction. While making an effort to follow Michelangelo's plan, Maderno added a three bay nave (1609-1615) and in the facade (1607) succeeded in making an undetectable transition from the older centralized structure to his longitudinal addition. Maderno used some of the same principles featured at S. Susanna, progressive layering and a central focus marked with a pediment. Maderno added a secondary order on the lower story portals, which gives the facade a more human scale and adds to the overall rhythm.