Contrasting Effects of Solids and Cavities
Southeast of S. Peter's in Rome there is a Renaissance monument of unique classical beauty--the city gateway Porta di Santo Spirito, by Antonio da Sangallo.
It is rather difficult to decide what it is that gives this structure its noble character. Like the triumphal arches of ancient Rome it is composed entirely of familiar elements: a vaulted archway in a framework of columns and niches. But here, on the slightly curved front, every one of these old elements appears in a new and sublime form, amazingly whole and impressive. The niches in antique triumphal arches were for the most part simply small recesses designed to hold statues. In Porta di Santo Spirito the niche has acquired a more independent existence as a concave