No precedent before it, no easy equal after
The present building is the third church on this site, raised between 532 and 537 to the design of Anthemius of Tralles and Isidore of Miletus. For the first time at this scale, a dome was set not on a circular wall but on a square plan, carried by pendentives. A ring of forty windows encircles its base, some 31 metres across; the book looks past the dome to the arches and half-domes that hold it up.
Link to this section: No precedent before it, no easy equal after