The first of Ruskin’s three volumes on the architecture of Venice, this is a basic introduction to architecture in stone and brick with particular reference to Mediaeval architecture (the so-called Gothic style). The first half (after an introduction which is basically an attack on the Renaissance and the Catholic Church) describes the constructional principles, beginning at the base and going up through shafts, the wall, the cornice and the roof, then dealing with arches and apertures (doors and windows). The second half describes principles of ornamentation in the same order.
Ruskin has the merit of being one of the first critics to appreciate the art and architecture of the Middle Ages; in that respect he is the antipode of Vasari, my first reading in my art history project, who repudiates the entire period from the end of the Roman Empire to Cimabue and Giotto. On the other hand, he is one of those people who is temperamentally incapable of acknowledging more than one way as “right”, so he can only praise the Gothic style by repudiating the Renaissance and all later architecture and art (before Turner, of course.) For him, Cimabue and Giotto are not the beginning of the Renaissance but the final gasp of the Middle Ages before the Decline.
Ruskin is obnoxiously Christian and fanatically Protestant; again, there is only one way. He devotes part of his introductory chapter to a screed against Parliament for having recently allowed some civil rights to Catholics in England; he asks what would happen if that were applied to Ireland, and laments that the government lacks the moral courage to deport the majority of the population of Ireland (he doesn’t say where to) and replace them by “hard-working Protestants”. Throughout the book he brings in arguments from religion at the most unlikely places, and clearly as in the second volume of Modern Painters he bases his aesthetic preferences on religious considerations. He sees the Church of the Middle Ages as a composition of Protestant tendencies (responsible for what is good in Gothic art) and Papist tendencies (responsible for whatever is rigid or formalistic), and dates the decline of art to the separation of the two at the Reformation, when the Papists (or as he also calls them, the “Heathen Popes”) came to dominate art at the Renaissance.
Leaving aside the Renaissance and Catholic-bashing, and some of the value judgements, the book seems to be a good introduction to the principles of Gothic architecture, at least in its Italian incarnation, to the extent that I can judge (I have only read one other book on Gothic art, and that was about fifty years ago.) I learned a lot from it.