The Geometry of Love

In this book, Margaret Visser takes a detailed look at one church - the Church of St Agnes Outside the Walls, in Rome - and uses it as a study in architecture, history, etymology, culture, and theology. It is a beautifully-written, slow-moving tour of the entire church complex, spending time reflecting on all of the various parts, historical changes, personalities involved, and curious historical traditions still in evidence in this building.
Visser's writing really is beautiful, like a love letter to this church building and the faith of those who built and have maintained it. At times, her deep detail may be more academic than some readers want. The narrative of the building and the story of St Agnes sometimes takes a back seat to etymological explorations and details of ancient traditions, but these are all well-told stories that add to the significance of the building and its community.
Catacombs, martyrdom, monks, mystics, popes, saints, unwanted betrothals, scandal, brothels, dismembered holy relics, and more all get the spotlight in turn in this book. This would be a great read for anyone interested in Christianity, theology, saints, church architecture, or history. There are good notes for further reading and research if you're so inclined.